WO2022113937A1 - Carboxyl group-containing acrylic rubber, rubber composition, and rubber crosslink product - Google Patents

Carboxyl group-containing acrylic rubber, rubber composition, and rubber crosslink product Download PDF

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Publication number
WO2022113937A1
WO2022113937A1 PCT/JP2021/042818 JP2021042818W WO2022113937A1 WO 2022113937 A1 WO2022113937 A1 WO 2022113937A1 JP 2021042818 W JP2021042818 W JP 2021042818W WO 2022113937 A1 WO2022113937 A1 WO 2022113937A1
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Prior art keywords
carboxyl group
rubber
monomer
containing acrylic
acrylic rubber
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PCT/JP2021/042818
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French (fr)
Japanese (ja)
Inventor
宏 榊田
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日本ゼオン株式会社
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Priority to JP2022565325A priority Critical patent/JPWO2022113937A1/ja
Publication of WO2022113937A1 publication Critical patent/WO2022113937A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • C08F220/12—Esters of monohydric alcohols or phenols
    • C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
    • C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical

Definitions

  • the present invention relates to a carboxyl group-containing acrylic rubber, a rubber composition and a rubber crosslinked product, and more specifically, a carboxyl group-containing acrylic capable of giving a rubber crosslinked product having excellent processability and compression resistance and permanent strain resistance.
  • the present invention relates to rubber, and rubber compositions and rubber crosslinked products obtained by using such a carboxyl group-containing acrylic rubber.
  • Acrylic rubber is a polymer whose main component is a unit derived from a (meth) acrylic acid ester monomer, and is generally known as a rubber having excellent heat resistance, oil resistance, and ozone resistance, and is related to automobiles. Widely used in fields and the like.
  • acrylic rubber contains a carboxyl group from the viewpoint of improving water resistance while achieving excellent compression resistance and permanent strain resistance, and such carboxyl group is used.
  • a technique is disclosed in which the content of an anionic emulsifier contained in a group-containing acrylic rubber is within a specific range.
  • the carboxyl group-containing acrylic rubber disclosed in Patent Document 1 does not always have sufficient processability when various compounding agents are blended, and therefore, when it is made into a rubber crosslinked product, it has resistance to compression and permanent strain. It has been required to improve the processability when a compounding agent or the like is blended while maintaining the property.
  • the present invention has been made in view of such an actual situation, and provides a carboxyl group-containing acrylic rubber capable of providing a rubber crosslinked product having excellent processability and excellent compression-resistant permanent strain resistance. The purpose.
  • the present inventors have obtained a carboxyl group content in a carboxyl group-containing acrylic rubber containing a (meth) acrylic acid ester monomer unit and a carboxyl group-containing monomer unit. , And the amount of ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation is within a specific range, and the amount of change in the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is within a specific range. By doing so, it was found that the above object can be achieved, and the present invention has been completed.
  • the present invention is a carboxyl group-containing acrylic rubber containing a (meth) acrylic acid ester monomer unit and a carboxyl group-containing monomer unit.
  • the carboxyl group content is the number of moles of carboxyl groups per 100 g of the carboxyl group-containing acrylic rubber, and is in the range of 5.0 ⁇ 10 -3 to 1.5 ⁇ 10 ⁇ 2 mephr.
  • the amount of the ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation using the ethanol aqueous solution containing 75% by volume of ethanol and 25% by volume of water is 3.0 to 8.0% by weight.
  • a carboxyl group-containing acrylic rubber in which the amount of change in the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is in the range of 0.2 ⁇ 10 -3 to 1.2 ⁇ 10 -3 mephr. To.
  • the carboxyl group-containing acrylic rubber of the present invention it is preferable that the carboxyl group-containing monomer unit is a butendionic acid monoester monomer unit. In the carboxyl group-containing acrylic rubber of the present invention, it is preferable that the carboxyl group-containing monomer unit is a fumaric acid monoester monomer unit. In the carboxyl group-containing acrylic rubber of the present invention, the extraction amount of the aqueous ethanol solution is preferably 4.0 to 6.5% by weight.
  • the amount of change in the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is in the range of 0.5 ⁇ 10 -3 to 0.8 ⁇ 10 -3 mephr. It is preferable to have.
  • a rubber composition containing the above-mentioned carboxyl group-containing acrylic rubber-containing rubber component and a cross-linking agent. Further, according to the present invention, there is provided a rubber crosslinked product obtained by cross-linking the rubber composition described above.
  • the carboxyl group-containing acrylic rubber of the present invention contains a (meth) acrylic acid ester monomer unit and a carboxyl group-containing monomer unit.
  • the carboxyl group content is the number of moles of carboxyl groups per 100 g of the carboxyl group-containing acrylic rubber, and is in the range of 5.0 ⁇ 10 -3 to 1.5 ⁇ 10 ⁇ 2 mephr.
  • the amount of the ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation using the ethanol aqueous solution containing 75% by volume of ethanol and 25% by volume of water is 3.0 to 8.0% by weight.
  • the amount of change in the carboxyl group content when the extraction is performed by the ethanol aqueous solution extraction operation is in the range of 0.2 ⁇ 10 -3 to 1.2 ⁇ 10 -3 mephr.
  • the carboxyl group-containing acrylic rubber of the present invention is a (meth) acrylic acid ester monomer as a main component (in the present invention, a rubber having 50% by weight or more in the total rubber monomer unit) in the molecule.
  • a (meth) acrylic acid ester monomer as a main component (in the present invention, a rubber having 50% by weight or more in the total rubber monomer unit) in the molecule.
  • Anlic acid ester monomer and / or methacrylic acid ester monomer hereinafter, the same applies to methyl (meth) acrylate and the like.
  • the (meth) acrylic acid ester monomer forming the (meth) acrylic acid ester monomer unit is not particularly limited, and is, for example, a (meth) acrylic acid alkyl ester monomer and a (meth) acrylic acid alkoxy. Alkoxy ester monomers and the like can be mentioned.
  • the (meth) acrylic acid alkyl ester monomer is not particularly limited, but is an ester of an alkanol having 1 to 12 carbon atoms and a (meth) acrylic acid (a (meth) acrylic acid having an alkyl group having 1 to 12 carbon atoms.
  • Esters are preferable, and esters of alkanols having 1 to 8 carbon atoms and (meth) acrylic acid ((meth) acrylic acid esters having an alkyl group having 1 to 8 carbon atoms) are more preferable, and alkanols having 2 to 6 carbon atoms are more preferable.
  • an ester of (meth) acrylic acid (a (meth) acrylic acid ester having an alkyl group having 2 to 6 carbon atoms) is more preferable.
  • (meth) acrylic acid alkyl ester monomer examples include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and (meth) acrylic.
  • examples thereof include n-butyl acid, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylate.
  • ethyl (meth) acrylate and n-butyl (meth) acrylate are preferable, and ethyl acrylate and n-butyl acrylate are more preferable. These can be used alone or in combination of two or more.
  • the (meth) acrylic acid alkoxyalkyl ester monomer is not particularly limited, but has an ester of an alkoxyalkyl alcohol having 2 to 12 carbon atoms and an (meth) acrylic acid (having an alkoxyalkyl group having 2 to 12 carbon atoms).
  • (Meta) acrylic acid ester) is preferable, and an ester of an alkoxyalkyl alcohol having 2 to 8 carbon atoms and (meth) acrylic acid (a (meth) acrylic acid ester having an alkoxyalkyl group having 2 to 8 carbon atoms) is more preferable.
  • An ester of an alkoxyalkyl alcohol having 2 to 6 carbon atoms and a (meth) acrylic acid (a (meth) acrylic acid ester having an alkoxyalkyl group having 2 to 6 carbon atoms) is more preferable.
  • (meth) acrylic acid alkoxyalkyl ester monomer examples include (meth) acrylic acid methoxymethyl, (meth) acrylic acid ethoxymethyl, (meth) acrylic acid 2-methoxyethyl, and (meth) acrylic acid 2-.
  • examples thereof include ethoxyethyl, 2-propoxyethyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, and 4-methoxybutyl (meth) acrylate.
  • 2-ethoxyethyl (meth) acrylate and 2-methoxyethyl (meth) acrylate are preferable, and 2-ethoxyethyl acrylate and 2-methoxyethyl acrylate are particularly preferable. These can be used alone or in combination of two or more.
  • the content of the (meth) acrylic acid ester monomer unit in all the monomer units constituting the carboxyl group-containing acrylic rubber of the present invention is preferably 70 to 99.9% by weight, more preferably 80. It is 99.5% by weight, more preferably 90 to 99% by weight, and particularly preferably 97 to 99% by weight.
  • the (meth) acrylic acid ester monomer unit is 30 to 100% by weight of the (meth) acrylic acid alkyl ester monomer unit, and the (meth) acrylic acid alkoxyalkyl. It is preferably composed of 70 to 0% by weight of the ester monomer unit, 90 to 100% by weight of the (meth) acrylic acid alkyl ester monomer unit, and 10 of the (meth) acrylic acid alkoxyalkyl ester monomer unit. It is more preferably composed of ⁇ 0% by weight, and it is composed of 100% by weight of the (meth) acrylic acid alkyl ester monomer unit and 0% by weight of the (meth) acrylic acid alkoxyalkyl ester monomer unit.
  • the obtained rubber crosslinked product has sufficient oil resistance and cold resistance. Can be.
  • the carboxyl group-containing monomer forming the carboxyl group-containing monomer unit is not particularly limited, and is, for example, ⁇ , ⁇ -ethylenic unsaturated monocarboxylic acid, ⁇ , ⁇ -ethylenic unsaturated dicarboxylic acid, and Examples thereof include ⁇ and ⁇ -ethylenic unsaturated dicarboxylic acid monoesters.
  • the acrylic rubber can be made into a carboxyl group-containing acrylic rubber having a carboxyl group as a cross-linking point, whereby the compression-resistant permanent strain in the case of a rubber cross-linked product can be obtained. The sex can be appropriately enhanced.
  • the ⁇ , ⁇ -ethylenically unsaturated monocarboxylic acid is not particularly limited, but ⁇ , ⁇ -ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms is preferable, and specific examples thereof include acrylic acid and methacrylic acid. , ⁇ -Ethylacrylic acid, crotonic acid, cinnamic acid and the like.
  • the ⁇ , ⁇ -ethylenic unsaturated dicarboxylic acid is not particularly limited, but ⁇ , ⁇ -ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms is preferable, and specific examples thereof include fumaric acid and maleic acid.
  • the ⁇ , ⁇ -ethylenically unsaturated dicarboxylic acid monoester is not particularly limited, but a monoester of ⁇ , ⁇ -ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and alkanol is preferable, and 4 to 6 carbon atoms are preferable.
  • the monoester of ⁇ , ⁇ -ethylenically unsaturated dicarboxylic acid and alkanol is more preferable, and the monoester of butendionic acid having 4 carbon atoms and alkanol is even more preferable.
  • butendionic acid monoester is preferable.
  • alkanol those having 1 to 12 carbon atoms are preferable, those having 2 to 8 carbon atoms are more preferable, and those having 2 to 6 carbon atoms are further preferable.
  • Specific examples of the ⁇ , ⁇ -ethylenic unsaturated dicarboxylic acid monoester include butendione such as monomethyl fumarate, monoethyl fumarate, mono n-butyl fumarate, monomethyl maleate, monoethyl maleate, and mono n-butyl maleate.
  • Acid monochain alkyl ester butendionic acid monoester having an alicyclic structure such as monocyclopentyl fumarate, monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate, monocyclohexenyl maleate; Examples thereof include monomethyl itaconate, monoethyl itaconate, monon-butyl itaconate, monoester of itaconate such as monocyclohexyl itaconate; and the like.
  • fumaric acid monoester is preferable, and fumaric acid mono-n-butyl is more preferable.
  • These ⁇ , ⁇ -ethylenically unsaturated carboxylic acid monomers can be used alone or in combination of two or more.
  • the dicarboxylic acid includes those existing as an anhydride.
  • the content of the carboxyl group-containing monomer unit in all the monomer units constituting the carboxyl group-containing acrylic rubber of the present invention is such that the carboxyl group content in the carboxyl group-containing acrylic rubber is in the above range. However, it is preferably 0.01% by weight or more, more preferably 0.01 to 20% by weight, still more preferably 0.1 to 10% by weight, still more preferably 0.5 to 5% by weight. Particularly preferably, it is 1 to 3% by weight.
  • the carboxyl group-containing acrylic rubber of the present invention has a (meth) acrylic acid ester monomer unit and a carboxyl group-containing monomer unit, as well as other monomer units copolymerizable with these. May be.
  • the other such copolymerizable monomer is not particularly limited, but is a monomer having an epoxy group, a monomer having a halogen atom, a diene monomer, an aromatic vinyl monomer, ⁇ , Examples thereof include ⁇ -ethylenic unsaturated nitrile monomer, acrylamide-based monomer, ⁇ , ⁇ -ethylenic unsaturated dicarboxylic acid diester monomer, and other olefin-based monomers.
  • the monomer having an epoxy group is not particularly limited, and for example, an epoxy group-containing (meth) acrylic acid ester such as glycidyl (meth) acrylate; an epoxy group-containing ether such as allyl glycidyl ether and vinyl glycidyl ether; and the like. Can be mentioned.
  • the monomer having a halogen atom is not particularly limited, and 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, or a (meth) acrylic.
  • examples thereof include acid (haloacetylcarbamoyloxy) alkyl esters, halogen-containing unsaturated ethers, halogen-containing unsaturated ketones, halomethyl group-containing aromatic vinyl compounds, halogen-containing unsaturated amides, and haloacetyl group-containing unsaturated monomers.
  • the monomer having a halogen atom preferably contains a chlorine atom as the halogen atom.
  • the unsaturated alcohol ester of the halogen-containing saturated carboxylic acid include vinyl chloroacetate, vinyl 2-chloropropionate, and allyl chloroacetic acid.
  • Specific examples of the (meth) acrylic acid haloalkyl ester include (meth) acrylic acid chloromethyl, (meth) acrylic acid 1-chloroethyl, (meth) acrylic acid 2-chloroethyl, and (meth) acrylic acid 1,2-dichloroethyl. , 2-chloropropyl (meth) acrylic acid, 3-chloropropyl (meth) acrylic acid, and 2,3-dichloropropyl (meth) acrylic acid.
  • (meth) acrylic acid haloacyloxyalkyl ester examples include (meth) acrylic acid 2- (chloroacetoxy) ethyl, (meth) acrylic acid 2- (chloroacetoxy) propyl, and (meth) acrylic acid 3- (chloro). Examples thereof include acetoxy) propyl and 3- (hydroxychloroacetoxy) propyl (meth) acrylate.
  • (meth) acrylic acid (haloacetylcarbamoyloxy) alkyl ester examples include (meth) acrylic acid 2- (chloroacetylcarbamoyloxy) ethyl and (meth) acrylic acid 3- (chloroacetylcarbamoyloxy) propyl. Can be mentioned.
  • halogen-containing unsaturated ether examples include chloromethyl vinyl ether, 2-chloroethyl vinyl ether, 3-chloropropyl vinyl ether, 2-chloroethyl allyl ether, 3-chloropropyl allyl ether and the like.
  • halogen-containing unsaturated ketone examples include 2-chloroethyl vinyl ketone, 3-chloropropyl vinyl ketone, 2-chloroethyl allyl ketone and the like.
  • halomethyl group-containing aromatic vinyl compound examples include p-chloromethylstyrene, m-chloromethylstyrene, o-chloromethylstyrene, and p-chloromethyl- ⁇ -methylstyrene.
  • halogen-containing unsaturated amide examples include N-chloromethyl (meth) acrylamide.
  • haloacetyl group-containing unsaturated monomer examples include 3- (hydroxychloroacetoxy) propyl allyl ether and p-vinylbenzylchloroacetic acid ester.
  • Examples of the diene monomer include a conjugated diene monomer and a non-conjugated diene monomer.
  • Specific examples of the conjugated diene monomer include 1,3-butadiene, isoprene, piperylene and the like.
  • Specific examples of the non-conjugated diene monomer include ethylidene norbornene, dicyclopentadiene, dicyclopentadienyl (meth) acrylate, and 2-dicyclopentadienyl ethyl (meth) acrylate.
  • Examples of the aromatic vinyl monomer include styrene, ⁇ -methylstyrene, divinylbenzene and the like.
  • Examples of the ⁇ , ⁇ -ethylenically unsaturated nitrile monomer include acrylonitrile and methacrylonitrile.
  • Examples of the acrylamide-based monomer include acrylamide and methacrylamide.
  • the ⁇ , ⁇ -ethylenic unsaturated dicarboxylic acid diester monomer is a maleic acid dialkyl ester such as dimethyl maleate or din-butyl maleate having an alkyl group having 1 to 18 carbon atoms; fumaric acid.
  • a fumaric acid dialkyl ester such as dimethyl or din-butyl fumarate having an alkyl group having 1 to 18 carbon atoms; a dicyclopentyl maleate such as dicyclopentyl maleate or dicyclohexyl maleate and a cycloalkyl ester.
  • olefin-based monomers include ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, ethyl vinyl ether, and butyl vinyl ether.
  • copolymerizable monomers can be used alone or in combination of two or more.
  • the content of the units of these other copolymerizable monomers in the monomer unit constituting the carboxyl group-containing acrylic rubber of the present invention is preferably 29.9% by weight or less, more preferably 15. It is 0% by weight or less, more preferably 9% by weight or less, and particularly preferably 4.5% by weight or less.
  • the content thereof may be in the above range, but among them, ethylene.
  • the content of the ethylene unit in the monomer unit constituting the carboxyl group-containing acrylic rubber of the present invention is preferably 9% by weight or less, preferably 4.5% by weight. The following is more preferable.
  • the carboxyl group-containing acrylic rubber of the present invention has an acrylonitrile unit or a methacrylonitrile unit, the total content of the acrylonitrile unit and the methacrylonitrile unit shall be 9% by weight or less. It is preferably 4.5% by weight or less, and more preferably 4.5% by weight or less.
  • the carboxyl group-containing acrylic rubber of the present invention has a carboxyl group content of 5.0 ⁇ 10 -3 to 1.5 ⁇ 10 -2 mephr (the number of moles of carboxyl groups per 100 g of the carboxyl group-containing acrylic rubber). It is in the range of molar equivalent per undred rubber).
  • the carboxyl group content in the carboxyl group-containing acrylic rubber is within the above range, and the ethanol aqueous solution extraction amount extracted by the ethanol aqueous solution extraction operation described later is 3.0 to 8.0% by weight.
  • the amount of change in the carboxyl group content when extracting by the ethanol aqueous solution extraction operation is in the range of 0.2 ⁇ 10 -3 to 1.2 ⁇ 10 -3 mephr. It is possible to make the contained acrylic rubber excellent in processability and excellent compression resistance and permanent strain resistance when it is made into a rubber crosslinked product.
  • the carboxyl group content of the carboxyl group-containing acrylic rubber of the present invention may be in the range of 5.0 ⁇ 10 -3 to 1.5 ⁇ 10 ⁇ 2 mephr, but is preferably 7.0 ⁇ 10 -3 to 1. .2 ⁇ 10 -2 mephr, more preferably 9.0 ⁇ 10 -3 to 1.05 ⁇ 10 -2 mephr. If the carboxyl group content is too low or too high, the obtained rubber crosslinked product will be inferior in compression set resistance.
  • the carboxyl group content of the carboxyl group-containing acrylic rubber is determined by, for example, dissolving the carboxyl group-containing acrylic rubber in acetone and adding water to the obtained solution to prepare a sample for measurement, which is alcoholic with respect to the sample for measurement. It can be measured by performing titration to the neutralization point using KOH and calculating the molar equivalent obtained from the amount of alcoholic KOH used for the titration.
  • the carboxyl group content of the carboxyl group-containing acrylic rubber can be adjusted, for example, by adjusting the amount of the carboxyl group-containing monomer unit contained in the carboxyl group-containing acrylic rubber, and more specifically, the carboxyl group.
  • the group-containing acrylic rubber can be adjusted by a method of adjusting the content of the carboxyl group-containing monomer in all the monomers used for polymerization, a method of adjusting the final polymerization conversion rate, or the like. can.
  • the monomer forming the carboxyl group-containing monomer unit is ⁇ from the viewpoint of improving the compression-resistant permanent strain resistance of the obtained rubber cross-linked product.
  • ⁇ -ethylenically unsaturated dicarboxylic acid monoester is preferable, butendionic acid monoester is more preferable, fumaric acid monoester is further preferable, and fumaric acid monon-butyl is particularly preferable. preferable.
  • the above-mentioned carboxyl group content is preferably mainly the content of a carboxyl group derived from the ⁇ , ⁇ -ethylenic unsaturated dicarboxylic acid monoester monomer unit, and the butendionic acid monoester monomer unit.
  • the content of the carboxyl group derived from the above is more preferable, and the content of the carboxyl group derived from the fumaric acid monoester monomer unit is further preferable, and the content of the carboxyl group derived from the mono n-butyl fumarate unit is more preferable.
  • the content of is particularly preferable.
  • the carboxyl group-containing acrylic rubber of the present invention is extracted by an ethanol aqueous solution extraction operation using an ethanol aqueous solution containing 75% by volume of ethanol and 25% by volume of water (volume ratio at a temperature of 25 ° C.).
  • the amount of ethanol aqueous solution extracted is in the range of 3.0 to 8.0% by weight.
  • the amount of the aqueous ethanol solution extracted is preferably 4.0 to 6.5% by weight, more preferably 4.4 to 6.0% by weight.
  • the component extracted by the ethanol aqueous solution extraction operation is a polymer component having a relatively low molecular weight contained in the carboxyl group-containing acrylic rubber of the present invention, and usually has a molecular weight of 5,000 or more and ethanol.
  • the amount of the component extracted by such an ethanol aqueous solution extraction operation that is, the amount of the polymer component having a relatively low molecular weight is set within the above range to achieve such a relatively low molecular weight.
  • Excellent processability can be realized by the action of a certain polymer component. If the amount of ethanol aqueous solution extracted is too small, the carboxyl group-containing acrylic rubber will be inferior in processability, while if the amount of ethanol aqueous solution extracted is too large, the rubber cross-linked product will have resistance to compression and permanent strain. It will be inferior.
  • the ethanol aqueous solution extraction operation is performed as follows. That is, first, 1.5 g of carboxyl group-containing acrylic rubber is immersed in 150 ml of an ethanol aqueous solution containing 75% by volume of ethanol and 25% by volume of water, and the temperature is 90 ° C. in a heating device equipped with a reflux condenser. It is performed by repeating the operation of heating at the above temperature for 1.5 hours twice (that is, repeating the heating operation for 1.5 hours twice). Then, the carboxyl group-containing acrylic rubber after the ethanol aqueous solution extraction operation is dried, and the weight thereof is measured to obtain the weight W 1 of the carboxyl group-containing acrylic rubber after the ethanol aqueous solution extraction operation, and ethanol is used.
  • the amount of the carboxyl group-containing acrylic rubber extracted from the ethanol aqueous solution is, for example, the method for adjusting the polymerization conversion rate at the start of the post-reaction step in the method for producing the carboxyl group-containing acrylic rubber of the present invention, which will be described later, and the final polymerization conversion. It can be adjusted by a method of adjusting the rate or the like, but is not particularly limited to these methods.
  • the amount of change in the carboxyl group content when extracted by the ethanol aqueous solution extraction operation is the number of moles of carboxyl groups per 100 g of the carboxyl group-containing acrylic rubber. It is in the range of 2 ⁇ 10 -3 to 1.2 ⁇ 10 -3 mephr (molar equivalent per undred rubber).
  • the amount of change in the carboxyl group content when extracting by the ethanol aqueous solution extraction operation is the carboxyl group content A0 of the carboxyl group-containing acrylic rubber before the above-mentioned ethanol aqueous solution extraction operation and the above-mentioned ethanol aqueous solution extraction.
  • the carboxyl group content and the ethanol aqueous solution extraction amount of the carboxyl group-containing acrylic rubber are within the above ranges, and the change amount of the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is within the above range.
  • the present inventors have focused on polymer components having a relatively low molecular weight, such as components extracted by an ethanol aqueous solution extraction operation, and conducted a diligent study, and obtained the following findings. Is.
  • the processability can be improved by setting the amount of the polymer component having a relatively low molecular weight such as the component extracted by the ethanol aqueous solution extraction operation within a specific range, and on the other hand, the ethanol aqueous solution extraction can be performed. If the amount of carboxyl groups contained in the polymer component having a relatively low molecular weight such as the component extracted by the operation is too small or too large, the compression set resistance is lowered. It was found that the present invention was completed based on such findings. In particular, the present inventors have contributed to the improvement of compression resistance and permanent strain resistance by acting as a crosslinkable group in the carboxyl group-containing acrylic rubber, while the components extracted by the ethanol aqueous solution extraction operation. It has been found that controlling the amount of carboxyl groups contained in a polymer component having a relatively low molecular weight, such as the above, within a specific range contributes to the improvement of compression resistance and permanent strain resistance.
  • the amount of change in the carboxyl group content when the carboxyl group-containing acrylic rubber is extracted by the ethanol aqueous solution extraction operation may be in the range of 0.2 ⁇ 10 -3 to 1.2 ⁇ 10 -3 mephr. It is preferably in the range of 0.4 ⁇ 10 -3 to 1.0 ⁇ 10 -3 mephr, and more preferably in the range of 0.5 ⁇ 10 -3 to 0.8 ⁇ 10 -3 mephr. If the amount of change in the carboxyl group content is too small when the carboxyl group-containing acrylic rubber is extracted by the ethanol aqueous solution extraction operation, the carboxyl group-containing acrylic rubber becomes inferior in processability, while the carboxyl group. If the amount of change in the content is too large, the obtained crosslinked rubber product will be inferior in compressive permanent strain resistance, and the carboxyl group-containing acrylic rubber will also be inferior in processability.
  • the carboxyl group content of the carboxyl group-containing acrylic rubber after the ethanol aqueous solution extraction operation may be measured in the same manner as described above.
  • the amount of change in the carboxyl group content when the carboxyl group-containing acrylic rubber is extracted by the ethanol aqueous solution extraction operation is, for example, at the start of the post-reaction step in the method for producing the carboxyl group-containing acrylic rubber of the present invention, which will be described later.
  • a method for adjusting the polymerization conversion rate of the above, a method for adjusting the ratio of the carboxyl group-containing monomer in all the monomers contained in the polymerization reaction system at the start of the post-reaction step, and a method for adjusting the final polymerization conversion rate It can be adjusted by a method or the like, but is not particularly limited to these methods.
  • the amount of change in the carboxyl group content is mainly derived from the carboxyl group-containing monomer unit forming the carboxyl group-containing acrylic rubber. Therefore, the amount of change in the carboxyl group content is mainly derived from the ⁇ , ⁇ -ethylenically unsaturated dicarboxylic acid monoester from the viewpoint of improving the compression set resistance of the obtained rubber crosslinked product. It is more preferably the amount of change in the content of the carboxyl group, more preferably the amount of change in the content of the carboxyl group derived from the butenedioic acid monoester monomer unit, and the amount of change in the fumarate monoester monomer unit. It is more preferably the amount of change in the content of the derived carboxyl group, and particularly preferably the amount of change in the content of the carboxyl group derived from the mono-n-butyl fumarate unit.
  • the carboxyl group content after extraction of the carboxyl group-containing acrylic rubber by the ethanol aqueous solution extraction operation is not particularly limited, but is preferably 4.0 ⁇ 10 -3 to 1.4 ⁇ 10 -2 mepr. Yes, more preferably 6.0 ⁇ 10 -3 to 1.1 ⁇ 10 -2 mephr, and even more preferably 8.0 ⁇ 10 -3 to 9.05 ⁇ 10 -3 mephr.
  • the carboxyl group-containing acrylic rubber of the present invention has a Mooney viscosity (ML1 + 4,100 ° C.) in the range of 10 to 150, preferably in the range of 20 to 100, and more preferably in the range of 25 to 70.
  • Mooney viscosity ML1 + 4,100 ° C.
  • the weight average molecular weight (Mw) of the carboxyl group-containing acrylic rubber of the present invention is not particularly limited, but is preferably 800,000 or more, more preferably 800,000 or more from the viewpoint of improving mechanical strength and processability. It is preferably 800,000 to 2,600,000, more preferably 900,000 to 2,300,000, and particularly preferably 1,000,000 to 2,000,000.
  • the molecular weight distribution of the carboxyl group-containing acrylic rubber is not particularly limited, but the value of Mw / Mn is preferably 1.50 to 10.0, more preferably 1.70 to 8.00, and further preferably 1.70 to 8.00.
  • the weight average molecular weight and molecular weight distribution of the carboxyl group-containing acrylic rubber can be determined by, for example, the absolute molecular weight and the absolute molecular weight by the GPC-MALS method using a GPC (Gel Permeation Chromatography) apparatus incorporating a multi-angle laser light scattering photometric meter (MALS). It can be obtained as an absolute molecular weight distribution.
  • GPC Global Permeation Chromatography
  • the method for producing the carboxyl group-containing acrylic rubber of the present invention is not particularly limited, and any method may be adopted, but for example, the following method is suitable. That is, A monomer obtained by emulsifying a monomer component used for polymerization, which contains a (meth) acrylic acid ester monomer and a carboxyl group-containing monomer, with an emulsifier and water to obtain a monomer emulsified solution. Emulsification liquid preparation process and An initial polymerization step of initiating a polymerization reaction by adding a polymerization initiator to a part of the total amount of the monomeric emulsion prepared in the monomer emulsion preparation step.
  • a production method including a post-reaction step of adding a polymerization initiator and / or a molecular weight adjusting agent to the polymerization reaction system after completing the dropping of the monomer emulsion to continue the polymerization reaction is preferable. ..
  • a monomer component used for polymerization including a (meth) acrylic acid ester monomer and a carboxyl group-containing monomer, is emulsified with an emulsifier and water. This is a step of obtaining a monomer emulsion.
  • Examples of the monomer component used when preparing the monomer emulsion include the above-mentioned monomers, and suitable monomers are also as described above. Further, the amount of each monomer used may be appropriately selected so as to be within the above-mentioned composition range.
  • the emulsifier is not particularly limited, and examples thereof include nonionic emulsifiers, anionic emulsifiers, and cationic emulsifiers.
  • the nonionic emulsifier is not particularly limited, and is, for example, a polyoxyalkylene fatty acid ester such as a polyoxyethylene stearate ester or a polyoxyethylene sorbitan alkyl ester; a polyoxyalkylene alkyl ether such as a polyoxyethylene dodecyl ether; a polyoxyethylene.
  • Polyoxyalkylene alkyl phenyl ethers such as nonyl phenyl ethers; and the like. Among these, polyoxyalkylene alkyl ether and polyoxyalkylene alkyl phenyl ether are preferable, and polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether are more preferable.
  • the weight average molecular weight of the nonionic emulsifier (weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC)) is not particularly limited, but is usually 300 to 50,000, preferably 500 to 30,000, more preferably. It is in the range of 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, and is, for example, a salt of a fatty acid such as myristic acid, palmitic acid, oleic acid, or linolenic acid; an alkylbenzene sulfonate such as sodium dodecylbenzenesulfonate; a higher alcohol sulfate such as sodium laurylsulfate.
  • Phosphoric acid ester salts such as ester salts and sodium alkyl phosphates, preferably higher alcohol phosphoric acid ester salts such as sodium phosphates of alcohols having a hydrophobic group having 6 or more carbon atoms; alkyl sulfosuccinates and the like can be mentioned. ..
  • anionic emulsifiers phosphoric acid ester salts and higher alcohol sulfate ester salts are preferable, higher alcohol phosphoric acid ester salts and higher alcohol sulfate ester salts are more preferable, and higher alcohol phosphoric acid ester salts are even more preferable.
  • anionic emulsifiers can be used alone or in combination of two or more.
  • cationic emulsifier examples include alkyltrimethylammonium chloride, dialkylammonium chloride, benzylammonium chloride and the like.
  • emulsifiers can be used alone or in combination of two or more, but among them, nonionic emulsifiers and anionic emulsifiers are preferable, and nonionic emulsifiers and anionic emulsifiers are more preferable.
  • a nonionic emulsifier and an anionic emulsifier it is used in the coagulation step described later while effectively suppressing the generation of stains due to the adhesion of a polymer or the like to a polymerization apparatus (for example, a polymerization tank) during emulsion polymerization.
  • the amount of the emulsifier used is the total amount of the emulsifier used with respect to 100 parts by weight of the monomer component used for the polymerization, 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. It is the range of the part.
  • the ratio of use is usually 1/99 to 99/1, preferably 10/90 to 80/20, in terms of the weight ratio of the nonionic emulsifier / anionic emulsifier. , More preferably 13/87 to 40/60, and even more preferably 15/85 to 35/65.
  • the monomer emulsion preparation step as a method of emulsifying a monomer component used for polymerization, including a (meth) acrylic acid ester monomer and a carboxyl group-containing monomer, using water and an emulsifier, although not particularly limited, a method of mixing the monomer component, water, and an emulsifier is preferable, and a method of stirring the monomer component, water, and the emulsifier using a stirrer such as a homogenizer or a disk turbine is preferable. More preferred. If necessary, the monomeric emulsion may contain a polymerization auxiliary material such as a particle size adjusting agent, a chelating agent, and an oxygen scavenger.
  • a polymerization auxiliary material such as a particle size adjusting agent, a chelating agent, and an oxygen scavenger.
  • the amount of water used in the monomer emulsion preparation step is preferably 5 to 500 parts by weight, more preferably 10 to 300 parts by weight, still more preferably 20 to 20 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. It is 200 parts by weight.
  • the total amount of the monomer components used for the polymerization is set to the state of the monomer emulsion, and the initial polymerization step, the monomer emulsifying droplet lowering step, and the post-reaction step described later are performed.
  • This may be an embodiment such as obtaining a carboxyl group-containing acrylic rubber, but preferably 80 to 100% by weight, more preferably 90 to 100% by weight, out of 100% by weight of the total amount of the monomer components used for the polymerization.
  • the residue may be added separately in the initial polymerization step or the post-reaction step, which will be described later, without the state of the monomeric emulsion.
  • the initial polymerization step is a step of initiating the polymerization reaction by adding a polymerization initiator to a part of the total amount of the monomeric emulsion prepared in the above-mentioned monomeric emulsion preparation step.
  • the initial polymerization step a part of the total amount of the monomer emulsion prepared in the above-mentioned monomer emulsion preparation step is used to initiate the polymerization reaction, thereby mainly performing seed formation. It is a thing.
  • the polymerization initiator is not particularly limited, and those usually used in emulsion polymerization can be used without limitation.
  • the polymerization initiator for example, it is preferable to use a peroxide, an azo compound, or a redox-based polymerization initiator composed of a peroxide and a reducing agent.
  • peroxide either an inorganic peroxide or an organic peroxide may be used.
  • inorganic peroxide examples include sodium persulfate, potassium persulfate, hydrogen peroxide, ammonium persulfate and the like.
  • potassium persulfate, hydrogen peroxide, and ammonium persulfate are preferable, and potassium persulfate is particularly preferable.
  • organic peroxide examples include 2,2-di (4,4-di- (t-butylperoxy) cyclohexyl) propane, 1-di- (t-hexylperoxy) cyclohexane, and 1,1-.
  • azo compound examples include azobisisobutyronitrile, 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis [2- (2-imidazolin-2-yl) propane, 2, 2'-azobis (propane-2-carboamidine), 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropaneamide], 2,2'-azobis ⁇ 2- [1- (2) -Hydroxyethyl) -2-imidazolin-2-yl] propane ⁇ , 2,2'-azobis (1-imino-1-pyrrolidino-2-methylpropane), 2,2'-azobis ⁇ 2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propanamide ⁇ and the like can be mentioned.
  • the amount of the peroxide and the azo compound used in the initial polymerization step is preferably 0.001 to 0.020 parts by weight, more preferably 0.002 to 0 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. It is 015 parts by weight, more preferably 0.003 to 0.010 parts by weight.
  • the reducing agent used in combination with the peroxide can be used without limitation as long as it is used as a redox catalyst for emulsion polymerization.
  • As the reducing agent it is preferable to use at least two kinds of reducing agents, and among them, a combination of a metal ion compound in a reduced state and another reducing agent is preferable.
  • the metal ion compound in the reduced state is not particularly limited, and examples thereof include ferrous sulfate, sodium hexamethylenediamine tetraacetate, and ferrous naphthenate. Among these, ferrous sulfate is preferable.
  • the metal ion compound in the reduced state can be used alone or in combination of two or more.
  • the amount of the metal ion compound in the reduced state in the initial polymerization step is preferably 0.0005 to 0.0030 parts by weight, more preferably 0.0007 to 0, based on 100 parts by weight of the monomer component used for the polymerization. It is 0025 parts by weight, more preferably 0.0010 to 0.0020 parts by weight.
  • the reducing agent other than the metal ion compound in the reduced state is not particularly limited, and is, for example, ascorbic acid such as ascorbic acid, sodium ascorbate, potassium ascorbate or a salt thereof; Elysorbic acid or a salt thereof; sulphinates such as sodium formaldehyde sulfoxylate; sodium bisulfite, potassium sulfite, sodium bisulfite, sodium aldehyde bisulfite, sodium bisulfite sulfite; sodium pyrosulfite, potassium pyrosulfite, pyrosulfite Pyro sulfites such as sodium bisulfite and potassium hydrogen sulfite; thiosulfates such as sodium thiosulfite and potassium thiosulfite; phosphite, sodium bisulfite, potassium bisulfite, sodium bisulfite, potassium hydrogen phosphite Examples thereof include pyrophosphoric acid such as pyrophosphoric acid,
  • the reducing agent other than the metal ion compound in the reduced state can be used alone or in combination of two or more.
  • the amount of the reducing agent other than the metal ion compound in the reduced state in the initial polymerization step is preferably 0.005 to 0.080 parts by weight, more preferably 0, with respect to 100 parts by weight of the monomer component used for the polymerization. It is 010 to 0.060 parts by weight, more preferably 0.020 to 0.040 parts by weight.
  • a preferable combination of the metal ion compound in the reduced state and the reducing agent other than the metal ion compound in the reduced state is a combination of ferrous sulfate and ascorbic acid or a salt thereof and / or sodium formaldehyde sulfoxylate.
  • the combination of ferrous sulfate and ascorbic acid salt and / or sodium formaldehyde sulfoxylate is more preferable, and the combination of ferrous sulfate and sodium formaldehyde sulfoxylate is particularly preferable.
  • the amount of water used in the initial polymerization step is preferably 5 to 500 parts by weight, more preferably 10 to 300 parts by weight, still more preferably 20 to 200 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. be.
  • the polymerization temperature and the polymerization time in the initial polymerization step are not particularly limited, but the polymerization temperature is preferably 0 to 100 ° C, more preferably 5 to 80 ° C, and even more preferably 10 to 50 ° C.
  • the polymerization time is preferably 0.3 to 2.0 hours, more preferably 0.5 to 1.0 hours.
  • the initial polymerization step a part of the monomer components used for the polymerization is added to the polymerization reaction system as it is, not in the state of the monomer emulsion, to start the polymerization reaction in the initial polymerization step. May be.
  • the remainder of the monomer emulsifying liquid prepared in the monomer emulsifying liquid preparation step is continuously or continuously to the polymerization reaction system with respect to the polymerization reaction system that has undergone the initial polymerization step. It is a step of advancing the polymerization reaction by dropping.
  • the remainder of the monomer emulsifying solution prepared in the monomer emulsifying solution preparation step is continuously or continuously, preferably continuously dropped onto the polymerization reaction system.
  • the polymerization reaction is allowed to proceed, and the dropping time is not particularly limited at this time, but when the obtained carboxyl group-containing acrylic rubber is extracted by the ethanol aqueous solution extraction operation, at the start of the post-reaction step described later. From the viewpoint of controlling the polymerization conversion rate of the above, it is preferably 2.0 to 20 hours, more preferably 3.0 to 10.0 hours.
  • the polymerization reaction proceeds by continuously or continuously dropping the remainder of the monomeric emulsion prepared in the monomer emulsion preparation step onto the polymerization reaction system.
  • the polymerization initiator is continuously or continuously added dropwise to the polymerization reaction system, and the polymerization initiator is continuously added dropwise. It is more preferable to have such an embodiment.
  • the polymerization initiator it is preferable to use a peroxide, an azo compound, and a redox-based polymerization initiator composed of a peroxide and a reducing agent.
  • the polymerization initiator when the polymerization initiator is continuously or continuously added dropwise to the polymerization reaction system together with the rest of the monomeric emulsion, these are polymerized using separate dropping devices. It may be added dropwise to the system, or when a redox-based polymerization initiator composed of a peroxide and a reducing agent is used, at least the peroxide and the reducing agent are mixed in advance and, if necessary. It may be dropped onto the polymerization reaction system from the same dropping device as an aqueous solution.
  • the amount of the peroxide and the azo compound used in the step below the monomer emulsified droplet is preferably 0.003 to 0.020 part by weight, more preferably 0, with respect to 100 parts by weight of the monomer component used for the polymerization. It is 005 to 0.015 parts by weight, more preferably 0.006 to 0.012 parts by weight.
  • the amount of the reducing agent used in the step below the monomer emulsifying droplet is preferably 0.05 to 0.50 parts by weight, more preferably 0.10 to 0 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. It is 0.40 parts by weight, more preferably 0.15 to 0.35 parts by weight.
  • the polymerization temperature in the step below the monomer emulsification droplet is not particularly limited, but the polymerization temperature is preferably 0 to 100 ° C, more preferably 5 to 80 ° C, and even more preferably 10 to 50 ° C.
  • Post-reaction process In the post-reaction step, after the dropping of the monomer emulsifying solution in the above-mentioned step below the monomer emulsifying droplet is completed, a polymerization initiator and / or a molecular weight adjusting agent is added to the polymerization reaction system to continue the polymerization reaction. It is a process to be polymerized.
  • the polymerization reaction may be continued by adding a polymerization initiator and / or a molecular weight adjusting agent after the dropping of the monomer emulsifying solution in the above-mentioned monomer emulsifying droplet lower step is completed.
  • a polymerization initiator and / or a molecular weight adjusting agent after the dropping of the monomer emulsifying solution in the above-mentioned monomer emulsifying droplet lower step is completed.
  • Polymerization starts when the ratio is preferably 80 to 94%, more preferably 81 to 93%, still more preferably 83 to 92%, and even more preferably 85 to 91%. It is preferable to add an agent and / or a molecular weight adjusting agent to continue the polymerization reaction.
  • the polymerization conversion rate at the end of dropping the monomer emulsion in the step below the monomer emulsifying droplet is, for example, in combination with a polymerization initiator (for example, a peroxide, an azo compound or a peroxide) in the initial polymerization step.
  • a polymerization initiator for example, a peroxide, an azo compound or a peroxide
  • a method for adjusting the amount of the reducing agent used) and the amount of the polymerization initiator (for example, a peroxide, an azo compound or a reducing agent used in combination with the peroxide) in the lower step of the monomer emulsified droplet can be adjusted by a method of adjusting, a method of adjusting the dropping time in the step of lowering the monomer emulsified droplet, or the like. Then, in the post-reaction step, a polymerization initiator and / or a molecular weight adjusting agent is added when the polymerization conversion rate reaches the above range after the dropping of the monomer emulsifying solution in the step below the monomer emulsifying droplet is completed. Therefore, it is preferable to continue the polymerization reaction.
  • the polymerization initiator and / or a molecular weight adjusting agent is added when the polymerization conversion rate reaches the above range after the dropping of the monomer emulsifying solution in the step below the monomer
  • a polymerization initiator and / or a molecular weight adjusting agent is added to continue the polymerization reaction.
  • the formation of a polymer component having a relatively low molecular weight can be promoted, whereby the amount of the obtained carboxyl group-containing acrylic rubber extracted from the ethanol aqueous solution can be controlled. It is a thing. Therefore, in the post-reaction step, it is preferable to add a polymerization initiator and / or a molecular weight adjuster when the polymerization conversion rate is within the above range to continue the polymerization reaction.
  • the polymerization initiator used in the post-reaction step is not particularly limited, but it is preferable to use a peroxide, an azo compound, or a redox-based polymerization initiator composed of a peroxide and a reducing agent.
  • the amount of the peroxide and the azo compound used in the post-reaction step is preferably 0.015 to 0.045 parts by weight, more preferably 0.020 to 0, with respect to 100 parts by weight of the monomer component used for the polymerization. It is 040 parts by weight, more preferably 0.025 to 0.035 parts by weight.
  • the amount of the reducing agent used in the post-reaction step is preferably 0.004 to 0.015 parts by weight, more preferably 0.005 to 0.012 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. Parts, more preferably 0.006 to 0.010 parts by weight.
  • the molecular weight adjusting agent used in the post-reaction step is not particularly limited, but mercaptans such as n-butyl mercaptan and t-dodecyl mercaptan; sulfides such as tetraethylthium sulfide and diventamethylene thiuram hexasulfide; ⁇ -methyl. Sulfide dimer; carbon tetrachloride and the like can be mentioned.
  • the amount of the molecular weight adjusting agent used in the post-reaction step is preferably 0.006 to 0.020 parts by weight, more preferably 0.007 to 0.015 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. , More preferably 0.008 to 0.012 parts by weight.
  • a polymerization initiator and / or a molecular weight adjusting agent is added to the polymerization reaction system, and the final polymerization conversion rate (polymerization conversion rate when the polymerization in the post-reaction step is stopped) is preferable. Is 95% or more, more preferably 97% or more, still more preferably 98% or more, and it is preferable to continue the polymerization reaction.
  • the upper limit of the final polymerization conversion rate is not particularly limited, but is 99.5% or less.
  • a polymerization terminator When stopping the polymerization reaction, a polymerization terminator can be used.
  • 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 component used for the polymerization.
  • the carboxyl group-containing monomer has a relatively low polymerization reactivity as compared with other monomers, and is another single amount. It tends to remain more easily than the body. Therefore, at the start of the post-reaction step, the content ratio of the carboxyl group-containing monomer in all the monomers contained in the polymerization reaction system tends to be relatively high, and this tendency is taken into consideration. It is preferable to control the conditions for starting the polymerization related to the post-reaction step, for example, the polymerization conversion rate and the final polymerization conversion rate at the time of starting the post-reaction, thereby extracting by the ethanol aqueous solution extraction operation. The amount of change in the carboxyl group content (that is, the amount of the carboxyl group contained in the polymer component having a relatively low molecular weight) can be controlled.
  • the polymerization in the post-reaction step promotes the production of the polymer component having a relatively low molecular weight. Therefore, from the viewpoint of adjusting the amount of change in the carboxyl group content (that is, the amount of the carboxyl group contained in the polymer component having a relatively low molecular weight) when the extraction is performed by the ethanol aqueous solution extraction operation, the polymerization is carried out.
  • a method of adjusting the content ratio of the carboxyl group-containing monomer in all the monomers used a method of adding a part of the total amount of the carboxyl group-containing monomer used for polymerization in the initial polymerization step, and later.
  • a relatively large amount of the carboxyl group-containing monomer is polymerized at the initial stage of the polymerization. It can be present in the reaction system, whereby the consumption of the carboxyl group-containing monomer in the polymerization reaction can be promoted, and as a result, the polymerization reaction system at the time of initiating the polymerization related to the post-reaction step.
  • the content ratio of the carboxyl group-containing monomer in all the monomers contained therein can be relatively low.
  • the polymerization temperature in the post-reaction step is not particularly limited, but the polymerization temperature is preferably 0 to 100 ° C, more preferably 5 to 80 ° C, still more preferably 10 to 50 ° C.
  • the production method of the present invention preferably further includes a coagulation step of forming a hydrous crumb by contacting the emulsion polymerization solution obtained through the post-reaction step with the coagulant.
  • the coagulant is not particularly limited, and examples thereof include monovalent to trivalent metal salts.
  • the monovalent to trivalent metal salt is a salt containing a metal that becomes a 1 to trivalent metal ion when dissolved in water, and is not particularly limited, but is an inorganic acid selected from, for example, hydrochloric acid, nitric acid, sulfuric acid and the like.
  • salts of organic acids such as acetic acid and metals selected from sodium, potassium, lithium, magnesium, calcium, zinc, titanium, manganese, iron, cobalt, nickel, aluminum, tin and the like. Further, hydroxides of these metals and the like can also be used.
  • 1- to trivalent metal salt examples include sodium chloride, potassium chloride, lithium chloride, magnesium chloride, calcium chloride, zinc chloride, titanium chloride, manganese chloride, iron chloride, cobalt chloride, nickel chloride, aluminum chloride, and chloride.
  • Metal chlorides such as tin; Nitrate such as sodium nitrate, potassium nitrate, lithium nitrate, magnesium nitrate, calcium nitrate, zinc nitrate, titanium nitrate, manganese nitrate, iron nitrate, cobalt nitrate, nickel nitrate, aluminum nitrate, tin nitrate; sodium sulfate , Potassium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, titanium sulfate, manganese sulfate, iron sulfate, cobalt sulfate, nickel sulfate, aluminum sulfate, sulfates such as tin sulfate; and the like.
  • Nitrate such as sodium nitrate, potassium nitrate, lithium nitrate, magnesium nitrate, calcium nitrate, zinc nitrate, titanium
  • calcium chloride, sodium chloride, aluminum sulfate, magnesium chloride, magnesium sulfate, zinc chloride, zinc sulfate and sodium sulfate are preferable.
  • these can be used alone or in combination of two or more.
  • the amount of the coagulant used is preferably 0.01 to 100 parts by weight, more preferably 0.1 to 50 parts by weight, still more preferably 1 to 30 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. Is.
  • the amount of the coagulant to be used within the above range, the obtained carboxyl group-containing acrylic rubber can be made excellent in water resistance while the coagulation of the carboxyl group-containing acrylic rubber in the coagulation step is sufficient.
  • the temperature of the aqueous solution containing the coagulant (that is, the coagulation temperature) in the coagulation step is not particularly limited, but is preferably 50 ° C. or higher from the viewpoint of more preferably controlling the particle size of the hydrous crumb produced by coagulation. Yes, more preferably 50 to 95 ° C, still more preferably 60 to 90 ° C.
  • the water-containing crumb obtained in the above-mentioned solidification step is further provided with a washing step for washing.
  • the cleaning method in the cleaning step is not particularly limited, and examples thereof include a method of washing the water-containing crumb obtained by the above-mentioned coagulation step with water, and preferably, the water-containing crumb obtained by the above-mentioned coagulation step. Is mixed with water.
  • 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 mixed with the water-containing crumb is not particularly limited, but from the viewpoint of further improving the washing efficiency, 50 parts by weight or more with respect to 100 parts by weight of the monomer component used for the polymerization.
  • the amount is preferably 50 to 15,000 parts by weight, more preferably 100 to 10000 parts by weight, and particularly preferably 500 to 5000 parts by weight.
  • the washing time with water is not particularly limited, but is preferably 1 to 120 minutes, more preferably 2 to 60 minutes, and even more preferably 3 to 30 minutes.
  • the number of washings with water in the washing step is not particularly limited, and is preferably 1 to 10 times, more preferably 1 to 5 times, and further preferably 1 to 3 times.
  • the number of washings with water means the operation of adding water to the water-containing crumb, mixing the water-containing crumbs for a predetermined time, and then separating the water-containing crumbs from the water used for washing with water once. It is the number of times in the case of. That is, for example, when the number of washings with water is twice, water is added to the water-containing crumb, and then the water-containing crumb is mixed for a predetermined time, and then the water-containing crumb and the water used for washing are separated from each other.
  • water is added to the water-containing crumb, and then the water-containing crumb is mixed for a predetermined time, and then the water-containing crumb and the water used for washing are separated.
  • the number of washings is two or more, the temperature of the water used for washing, the amount of water, and the washing time may be the same or different.
  • pickling after washing with water, pickling may be further performed using an acid as a cleaning liquid.
  • an acid it is preferable to further wash with water, and the conditions for washing with water may be the same as those described above.
  • a drying step of drying the water-containing crumbs washed in the above-mentioned washing step may be further provided.
  • the method for drying the water-containing crumb is not particularly limited, and a conventional method may be used.
  • a dryer such as a hot air dryer, a vacuum dryer, an expander dryer, a kneader type dryer, or a screw type extruder is used for drying. How to do it.
  • the drying temperature of the hydrous crumb is not particularly limited, but is preferably 80 to 250 ° C, more preferably 90 to 200 ° C, and even more preferably 100 to 180 ° C.
  • the method for dehydrating the water-containing crumb is not particularly limited, and examples thereof include a method of draining water from the water-containing crumb using a dehydrator such as a centrifuge, a squeezer, or a screw type extruder. From the viewpoint that the water content of the water-containing crumb can be further reduced, a method using a squeezer and a screw type extruder is preferable, a method using a screw type extruder is particularly preferable, and a method using a screw type extruder is particularly preferable.
  • the crumbs can be dehydrated and dried in a continuous process, which can increase productivity.
  • a barrel unit composed of a plurality of barrel blocks and a twin-screw extruder having a pair of screws rotatably arranged inside the barrel unit can be preferably used.
  • the carboxyl group-containing acrylic rubber can be produced as described above.
  • the carboxyl group-containing acrylic rubber may be obtained in the state of a crumb, or a veiled rubber, that is, a carboxyl group-containing acrylic rubber veil (carboxyl group-containing acrylic formed into a mass having a predetermined shape). It may be obtained as rubber).
  • the rubber composition of the present invention contains the above-mentioned rubber component containing the carboxyl group-containing acrylic rubber of the present invention and a cross-linking agent.
  • the content ratio of the carboxyl group-containing acrylic rubber component of the present invention in the rubber component may be appropriately selected according to the purpose of use, but is preferably 51% by weight or more, more preferably 71% by weight or more, still more preferably. Is 86% by weight or more, particularly preferably 100% by weight (that is, an embodiment in which the rubber component is substantially composed of only a carboxyl group-containing acrylic rubber component).
  • the rubber other than the carboxyl group-containing acrylic rubber of the present invention constituting the rubber component is not particularly limited, but is limited to acrylic rubber other than the carboxyl group-containing acrylic rubber of the present invention, natural rubber, polybutadiene rubber, polyisoprene rubber, and styrene-butadiene.
  • examples thereof include rubber, acrylic nitrile-butadiene rubber, silicon rubber, fluororubber, olefin-based elastomer, styrene-based elastomer, vinyl chloride-based elastomer, polyester-based elastomer, polyamide-based elastomer, polyurethane-based elastomer, and polysiloxane-based elastomer.
  • the rubber other than the carboxyl group-containing acrylic rubber of the present invention can be used alone or in combination of two or more.
  • the shape of the carboxyl group-containing acrylic rubber of the present invention and the shape of the rubber other than the carboxyl group-containing acrylic rubber of the present invention are not particularly limited, but may be any of veil-like, sheet-like, and powder-like shapes. May be good.
  • the cross-linking agent is not particularly limited, but for example, a polyvalent amine compound such as a diamine compound and a conventionally known cross-linking agent such as a carbonate thereof; a polyvalent epoxy compound; can be used. These cross-linking agents can be used alone or in combination of two or more. Among these, it is preferable to use a polyvalent amine compound and a carbonate thereof from the viewpoint of further enhancing the compression set resistance of the obtained rubber crosslinked product.
  • the polyvalent amine compound and its carbonate are not particularly limited, but a polyvalent amine compound having 4 to 30 carbon atoms and a carbonate thereof are preferable.
  • Examples of such polyvalent amine compounds and carbonates thereof include aliphatic polyvalent amine compounds, carbonates thereof, and aromatic polyvalent amine compounds.
  • the aliphatic polyvalent amine compound and its carbonate are not particularly limited, and examples thereof include hexamethylenediamine, hexamethylenediamine carbamate, and N, N'-dicinnamylidene-1,6-hexanediamine. Among these, hexamethylenediamine carbamate is preferable.
  • the aromatic polyvalent amine compound is not particularly limited, and is, for example, 4,4'-methylenedianiline, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether.
  • the content of the cross-linking agent in the rubber composition of the present invention is preferably 0.001 to 20 parts by weight, more preferably 0, with respect to 100 parts by weight of the rubber component containing the carboxyl group-containing acrylic rubber of the present invention. It is 1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and particularly preferably 0.2 to 4 parts by weight.
  • the rubber composition of the present invention further contains a cross-linking accelerator.
  • the cross-linking accelerator is not particularly limited, but when the cross-linking agent is a polyvalent amine compound or a carbonate thereof, a guanidine compound, a diazabicycloalkene compound, an imidazole compound, a quaternary onium salt, or a tertiary agent is used.
  • a phosphine compound, an aliphatic monovalent secondary amine compound, an aliphatic monovalent tertiary amine compound and the like can be used.
  • guanidine compound a diazabicycloalkene compound, and an aliphatic monovalent secondary amine compound are preferable, and a guanidine compound and a diazabicycloalkene compound are particularly preferable.
  • These basic cross-linking promoters can be used alone or in combination of two or more.
  • guanidine compound examples include 1,3-di-o-tolylguanidine, 1,3-diphenylguanidine and the like.
  • diazabicycloalkene compound examples include 1,8-diazabicyclo [5.4.0] unde-7-sen, 1,5-diazabicyclo [4.3.0] no-5-nen and the like. ..
  • Specific examples of the imidazole compound include 2-methylimidazole and 2-phenylimidazole.
  • Specific examples of the quaternary onium salt include tetra n-butylammonium bromide and octadecyltri n-butylammonium bromide.
  • tertiary phosphine compound include triphenylphosphine and tri-p-tolylphosphine.
  • the aliphatic monovalent secondary amine compound is a compound in which two hydrogen atoms of ammonia are replaced with an aliphatic hydrocarbon group.
  • the aliphatic hydrocarbon group that replaces the hydrogen atom is preferably one having 1 to 30 carbon atoms.
  • Specific examples of the aliphatic monovalent secondary amine compound include dimethylamine, diethylamine, dipropylamine, diallylamine, diisopropylamine, di-n-butylamine, dit-butylamine, di-sec-butylamine, dihexylamine, and dihexylamine.
  • Examples thereof include heptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditridecylamine, ditetradecylamine, dipentadecylamine, disetylamine, di-2-ethylhexylamine, and dioctadecylamine.
  • the aliphatic monovalent tertiary amine compound is a compound in which all three hydrogen atoms of ammonia are replaced with an aliphatic hydrocarbon group.
  • the aliphatic hydrocarbon group that replaces the hydrogen atom is preferably one having 1 to 30 carbon atoms.
  • Specific examples of the aliphatic monovalent tertiary amine compound include trimethylamine, triethylamine, tripropylamine, triallylamine, triisopropylamine, tri-n-butylamine, tri-t-butylamine, tri-sec-butylamine, and trihexylamine. , Triheptylamine, Trioctylamine, Trinonylamine, Tridecylamine, Triundecylamine, Tridodecylamine and the like.
  • the content of the crosslinking accelerator in the rubber composition of the present invention is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the rubber component containing the carboxyl group-containing acrylic rubber of the present invention. Is 0.5 to 7.5 parts by weight, particularly preferably 1 to 5 parts by weight.
  • the rubber composition of the present invention further contains a filler.
  • the filler is not particularly limited, and examples thereof include a reinforcing filler and a non-reinforcing filler. Among these, 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 non-reinforcing fillers include quartz powder, clay such as silica soil, zinc flower, basic magnesium carbonate, active calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, aluminum sulfate, and calcium sulfate. Examples include barium sulfate.
  • the content of the filler in the rubber composition of the present invention is not particularly limited, but is preferably 1 to 200 parts by weight, based on 100 parts by weight of the rubber component containing the carboxyl group-containing acrylic rubber of the present invention. It is preferably 10 to 150 parts by weight, more preferably 20 to 100 parts by weight.
  • a compounding agent usually used in the rubber processing field can be blended.
  • compounding agents include anti-aging agents; light stabilizers; anti-scorch agents; plasticizers; processing aids; pressure-sensitive adhesives; lubricants; lubricants; flame retardants; fungicides; antistatic agents; coloring agents. ; Crosslink retardant; etc.
  • the blending amount of these blending agents is not particularly limited as long as the purpose and effect of the present invention are not impaired, and an amount suitable for the blending purpose can be appropriately blended.
  • a cross-linking agent and various other compounding agents used as necessary are blended with the above-mentioned rubber component containing the carboxyl group-containing acrylic rubber of the present invention, and an open roll, a Banbury mixer, and various kneaders are blended. It is prepared by mixing and kneading with a kneading roll, and then further kneading with a kneading roll.
  • the blending order of each component is not particularly limited, but after sufficiently mixing the components that are difficult to react or decompose by heat, the cross-linking agent, which is a component that easily reacts or decomposes by heat, is mixed at a temperature at which reaction or decomposition does not occur. It is preferable to mix in a short time.
  • the rubber crosslinked product of the present invention is obtained by cross-linking the above-mentioned rubber composition of the present invention.
  • the rubber crosslinked 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 performing 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 120 ° C.
  • the crosslinking temperature is usually 130 to 220 ° C., preferably 150 to 190 ° C.
  • the crosslinking time is usually 2 minutes to 10 hours, preferably 3 minutes to 5 hours.
  • 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.
  • 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 rubber crosslinked product of the present invention is an O-ring, packing, diaphragm, oil seal, shaft seal, bearing sheath, mechanical seal, well head seal, seal for electric / electronic equipment, air compression equipment.
  • Sealing material such as seals; cylinder head gasket attached to the connection between the cylinder block and the cylinder head, rocker cover gasket attached to the connection between the rocker cover and the cylinder head, oil pan and the cylinder head or transmission case.
  • gaskets such as oil pan gaskets mounted on the connecting part of the fuel cell separator, gaskets for fuel cell separators mounted between a pair of housings sandwiching a unit cell equipped with a positive electrode, an electrolyte plate and a negative electrode, and gaskets for the top cover of a hard disk drive; It is suitably used as a cushioning material, a vibration-proof material; an electric wire coating material; an industrial belt, a tube / hose, a sheet, and the like.
  • the rubber crosslinked product of the present invention is used as an extruded product and a crosslinked product used in automobile applications, for example, fuel hose, filler neck hose, vent hose, vapor hose and other fuel oil hoses, turbo air hose, mission control. It is suitably used for various hoses such as air hoses such as hoses, radiator hoses, heater hoses, brake hoses, and air conditioner hoses.
  • Mooney viscosity (ML1 + 4, 100 ° C.) of rubber composition was measured according to JIS K6300: 2013, and processability was evaluated according to the following criteria. .. In the following criteria, the higher the score, the better the workability.
  • Mooney viscosity of rubber composition is 35 or more and less than 55 4 points: Mooney viscosity of rubber composition is 30 or more and less than 35, or 55 or more and less than 65 3 points: Mooney viscosity of rubber composition is 25 or more Less than 30 or 65 or more and less than 75 2 points: Mooney viscosity of rubber composition is 20 or more and less than 25, or 75 or more and less than 85 1 point: Mooney viscosity of rubber composition is less than 20 or 85 or more
  • the rubber composition was extruded using a uniaxial extruder and a garve die, and the surface skin smoothness was evaluated according to ASTM D2230.
  • the surface skin smoothness was evaluated according to the following criteria. In the following criteria, the higher the score, the better the extrusion processability.
  • the sheet surface is smooth and glossy and there is no air bubble entrainment 4 points: The sheet surface is smooth and glossy and there is some air bubble entrainment 3 points: The sheet surface is smooth but glossy No 2 points: There are rough skin parts such as unevenness and fine wrinkles on the sheet surface, but there are no holes in the sheet 1 point: There are rough skin parts such as unevenness and fine wrinkles on the sheet surface, and there are holes in the sheet
  • the rubber composition is primarily crosslinked by pressing it at a temperature of 170 ° C. for 20 minutes using a mold to obtain a cylindrical primary crosslinked product having a diameter of 29 mm and a height of 12.7 mm. Then, the obtained primary crosslinked product was further heated in a gear type oven at 170 ° C. for 4 hours for secondary cross-linking to obtain a columnar rubber crosslinked product. Then, using the obtained rubber crosslinked product, the rubber crosslinked product was placed in an environment of 175 ° C. for 70 hours in a state of being compressed by 25% according to JIS K6262: 2006, and then the compression permanent strain rate was measured. The smaller this value, the better the compression resistance and permanent strain resistance.
  • Example 1 Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-1)) Monomer emulsion preparation step In a mixing container equipped with a homomixer, 48.2 parts of pure water, 45 parts of ethyl acrylate, 53.2 parts of n-butyl acrylate, 1.8 parts of mono-n-butyl fumarate.
  • Sodium lauryl sulfate as an anionic surfactant (trade name "Emar 2FG”, manufactured by Kao Co., Ltd.) 1.5 parts
  • Polyoxyethylene dodecyl ether as a nonionic surfactant (trade name "Emargen 105", GPC measurement)
  • Weight average molecular weight in terms of polystyrene Approximately 1500, manufactured by Kao Co., Ltd.) 0.3 parts and 0.01 part of ethylenediamine tetraacetic acid (EDTA) are charged and stirred to obtain 150 parts of monomeric emulsion. rice field.
  • EDTA ethylenediamine tetraacetic acid
  • the temperature in the polymerization reaction tank is set to 35 ° C. While the temperature was raised and the temperature was maintained at 35 ° C., 0.003 part of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of cumene hydroperoxide were added for 1 hour.
  • the post-reaction was carried out by continuing the reaction, and when the polymerization conversion rate reached 98.2%, hydroquinone as a polymerization terminator was added to terminate the polymerization reaction to obtain an emulsified polymerization solution.
  • the obtained emulsified polymer solution is transferred to a coagulation tank, 60 parts of industrial water is added to 100 parts of this emulsified polymer solution, and the temperature is raised to 85 ° C.
  • a hydrous crumb was obtained by continuously adding 10 parts of magnesium sulfate as a coagulant while stirring the mixed solution at a temperature of 85 ° C. to coagulate the polymer and separate it by filtration.
  • 3000 parts of industrial water was added to 100 parts of the solid content of the water-containing crumb obtained above, and the mixture was stirred at room temperature for 5 minutes in the coagulation tank, and then the water was discharged from the coagulation tank to contain water.
  • the crumb was washed with water.
  • the hydrous crumb after washing with water was dried in a hot air dryer at 110 ° C. for 1 hour to obtain a solid carboxyl group-containing acrylic rubber (A-1).
  • the obtained carboxyl group-containing acrylic rubber (A-1) has a molecular weight of 5000 or more in an amount of 85% by weight or more. Therefore, the ethanol aqueous solution extraction amount has a relatively low molecular weight.
  • Example 2 Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-2)
  • A-2 Manufacturing of Carboxyl Group-Containing Acrylic Rubber
  • the compounding amount of ethyl acrylate was changed to 42.5 parts and the compounding amount of n-butyl acrylate was changed to 50.7 parts in the monomer emulsion preparation step, the initial polymerization step and the monomer emulsion.
  • Preparation of monomeric emulsion was prepared in the same manner as in Example 1 except that the amounts of ferrous sulfate, sodium formaldehyde sulfoxylate, and cumene hydroperoxide used in the dropping step were the amounts shown in Table 1.
  • a step, an initial polymerization step and a monomer emulsifying droplet lowering step were performed.
  • the temperature in the polymerization reaction tank was raised to 35 ° C. Keeping the temperature at 35 ° C., 2.5 parts of ethyl acrylate, 2.5 parts of n-butyl acrylate, 0.003 parts of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of Kumen hydroperoxide was added and the reaction was continued for 1 hour to carry out the post-reaction.
  • Example 3 Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-3)
  • A-3 Monomer emulsion preparation step
  • 0.36 parts of mono n-butyl fumarate was separately blended in the initial polymerization step.
  • the amounts of ferrous sulfate, sodium formaldehyde sulfoxylate, and cumene hydroperoxide used in the initial polymerization step and the monomer emulsification droplet lowering step were set to the amounts shown in Table 1.
  • a monomer emulsion preparation step, an initial polymerization step, and a monomer emulsifying droplet lowering step were performed.
  • the temperature in the polymerization reaction tank was raised to 35 ° C. While keeping the temperature at 35 ° C., 0.003 part of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of cumene hydroperoxide are added, and the reaction is continued for 1 hour.
  • Example 4 Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-4)
  • A-4 Manufacturing of Carboxyl Group-Containing Acrylic Rubber
  • Example 5 Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-5)
  • A-5 Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-5)
  • the monomer emulsion preparation step the single amount was the same as in Example 1 except that the blending amount of ethyl acrylate was changed to 55 parts and the blending amount of n-butyl acrylate was changed to 43.2 parts.
  • a body emulsion preparation step, an initial polymerization step, and a monomer emulsifying droplet lowering step were performed.
  • the temperature in the polymerization reaction tank was raised to 35 ° C. While keeping the temperature at 35 ° C., 0.003 part of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of cumene hydroperoxide are added, and the reaction is continued for 1 hour.
  • the temperature in the polymerization reaction tank was raised to 35 ° C. While keeping the temperature at 35 ° C., 0.003 part of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of cumene hydroperoxide are added, and the reaction is continued for 1 hour. Therefore, the post-reaction was carried out, and when the polymerization conversion rate reached 97.8%, hydroquinone as a polymerization terminator was added to terminate the polymerization reaction to obtain an emulsified polymerization solution. Then, the solidification step, the washing step, and the drying step were carried out in the same manner as in Example 1 to obtain a solid carboxyl group-containing acrylic rubber (A-6), and each measurement was carried out in the same manner. The results are shown in Table 1.
  • Example 2 Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-7)) Same as in Example 1 except that the amounts of ferrous sulfate, sodium formaldehyde sulfoxylate, and cumene hydroperoxide used in the initial polymerization step and the step below the monomer emulsified droplet were set to the amounts shown in Table 1. Then, a monomer emulsion preparation step, an initial polymerization step, and a monomer emulsifying droplet lowering step were performed.
  • the temperature in the polymerization reaction tank was raised to 35 ° C. While keeping the temperature at 35 ° C., 0.003 part of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of cumene hydroperoxide are added, and the reaction is continued for 1 hour. Therefore, the post-reaction was carried out, and when the polymerization conversion rate reached 98.1%, hydroquinone as a polymerization terminator was added to terminate the polymerization reaction to obtain an emulsified polymerization solution. Then, the solidification step, the washing step, and the drying step were carried out in the same manner as in Example 1 to obtain a solid carboxyl group-containing acrylic rubber (A-7), and each measurement was carried out in the same manner. The results are shown in Table 1.
  • the temperature in the polymerization reaction tank was raised to 35 ° C.
  • the post-reaction was carried out by continuing the reaction for 1 hour while keeping the temperature at 35 ° C., and when the polymerization conversion rate reached 94.0%, hydroquinone as a polymerization terminator was added to carry out the polymerization reaction.
  • hydroquinone as a polymerization terminator was added to carry out the polymerization reaction.
  • Comparative Examples 4 and 5 are the ones in which the polymerization reaction was carried out all at once, but the amount of each monomer, emulsifier, polymerization initiator used, etc. is the monomer emulsion preparation step. And described in the column of initial polymerization step.
  • the carboxyl group content is in the range of 5.0 ⁇ 10 -3 to 1.5 ⁇ 10 ⁇ 2 mephr, and the amount of ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation is 3.0. It is ⁇ 8.0% by weight, and the amount of change in the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is in the range of 0.2 ⁇ 10 -3 to 1.2 ⁇ 10 -3 mephr.
  • the carboxyl group-containing acrylic rubber is excellent in processability, and the rubber crosslinked product obtained by using the carboxyl group-containing acrylic rubber such as this is excellent in compression permanent strain resistance. (Examples 1 to 5).

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Abstract

Provided is a carboxyl group-containing acrylic rubber which contains a meth(acrylic) ester monomer unit and a carboxyl group-containing monomer unit, and in which: the carboxyl group content is in the range of 5.0×10-3-1.5×10-2mephr in terms of the number of moles per 100 g of the carboxyl group-containing acrylic rubber; an aqueous ethanol solution extraction amount of the carboxyl group-containing acrylic rubber, resulting from extraction through an aqueous ethanol solution extraction operation using an aqueous ethanol solution containing 75 vol% of ethanol and 25 vol% of water, is 3.0-8.0 wt%; and the amount of change in the carboxyl group content when extraction is performed by said aqueous ethanol solution extraction operation is in the range of 0.2×10-3-1.2×10-3mephr.

Description

カルボキシル基含有アクリルゴム、ゴム組成物およびゴム架橋物Carboxyl group-containing acrylic rubber, rubber composition and rubber crosslinked product
　本発明は、カルボキシル基含有アクリルゴム、ゴム組成物およびゴム架橋物に関し、さらに詳しくは、加工性に優れ、かつ、耐圧縮永久歪み性に優れたゴム架橋物を与えることのできるカルボキシル基含有アクリルゴム、ならびに、このようなカルボキシル基含有アクリルゴムを用いて得られるゴム組成物およびゴム架橋物に関する。 The present invention relates to a carboxyl group-containing acrylic rubber, a rubber composition and a rubber crosslinked product, and more specifically, a carboxyl group-containing acrylic capable of giving a rubber crosslinked product having excellent processability and compression resistance and permanent strain resistance. The present invention relates to rubber, and rubber compositions and rubber crosslinked products obtained by using such a carboxyl group-containing acrylic rubber.
　アクリルゴムは、（メタ）アクリル酸エステル単量体に由来の単位を主成分とする重合体であり、一般に耐熱性、耐油性および耐オゾン性に優れたゴムとして知られており、自動車関連の分野などで広く用いられている。 Acrylic rubber is a polymer whose main component is a unit derived from a (meth) acrylic acid ester monomer, and is generally known as a rubber having excellent heat resistance, oil resistance, and ozone resistance, and is related to automobiles. Widely used in fields and the like.
　たとえば、特許文献１には、優れた耐圧縮永久歪み性を実現しながら、耐水性の向上を可能とするという観点より、アクリルゴムを、カルボキシル基を含有するものとし、かつ、このようなカルボキシル基含有アクリルゴム中に含まれるアニオン性乳化剤の含有量を特定の範囲とする技術が開示されている。 For example, in Patent Document 1, acrylic rubber contains a carboxyl group from the viewpoint of improving water resistance while achieving excellent compression resistance and permanent strain resistance, and such carboxyl group is used. A technique is disclosed in which the content of an anionic emulsifier contained in a group-containing acrylic rubber is within a specific range.
国際公開第２０１８／０７９７８７号International Publication No. 2018/079787
　一方で、特許文献１に開示されているカルボキシル基含有アクリルゴムは、各種配合剤を配合した際における、加工性が必ずしも十分なものでなく、そのため、ゴム架橋物とした際における耐圧縮永久歪み性を維持しながら、配合剤等を配合した際における加工性を向上させることが求められていた。 On the other hand, the carboxyl group-containing acrylic rubber disclosed in Patent Document 1 does not always have sufficient processability when various compounding agents are blended, and therefore, when it is made into a rubber crosslinked product, it has resistance to compression and permanent strain. It has been required to improve the processability when a compounding agent or the like is blended while maintaining the property.
　本発明は、このような実状に鑑みてなされたものであり、加工性に優れ、かつ、耐圧縮永久歪み性に優れたゴム架橋物を与えることのできるカルボキシル基含有アクリルゴムを提供することを目的とする。 The present invention has been made in view of such an actual situation, and provides a carboxyl group-containing acrylic rubber capable of providing a rubber crosslinked product having excellent processability and excellent compression-resistant permanent strain resistance. The purpose.
　本発明者等は、上記目的を達成するために鋭意研究した結果、（メタ）アクリル酸エステル単量体単位およびカルボキシル基含有単量体単位を含有するカルボキシル基含有アクリルゴムについて、カルボキシル基含有量、および、エタノール水溶液抽出操作により抽出される、エタノール水溶液抽出量を特定の範囲とすること、さらには、エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量を特定の範囲とすることにより、上記目的を達成できることを見出し、本発明を完成させるに至った。 As a result of diligent research to achieve the above object, the present inventors have obtained a carboxyl group content in a carboxyl group-containing acrylic rubber containing a (meth) acrylic acid ester monomer unit and a carboxyl group-containing monomer unit. , And the amount of ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation is within a specific range, and the amount of change in the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is within a specific range. By doing so, it was found that the above object can be achieved, and the present invention has been completed.
　すなわち、本発明によれば、（メタ）アクリル酸エステル単量体単位およびカルボキシル基含有単量体単位を含有するカルボキシル基含有アクリルゴムであって、
　カルボキシル基含有量が、前記カルボキシル基含有アクリルゴム１００ｇ当たりのカルボキシル基のモル数で、５．０×１０－３～１．５×１０－２ｍｅｐｈｒの範囲であり、
　エタノールを７５体積％および水を２５体積％の割合で含有するエタノール水溶液を用いたエタノール水溶液抽出操作により抽出される、エタノール水溶液抽出量が３．０～８．０重量％であり、
　前記エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量が０．２×１０－３～１．２×１０－３ｍｅｐｈｒの範囲である、カルボキシル基含有アクリルゴムが提供される。 That is, according to the present invention, it is a carboxyl group-containing acrylic rubber containing a (meth) acrylic acid ester monomer unit and a carboxyl group-containing monomer unit.
The carboxyl group content is the number of moles of carboxyl groups per 100 g of the carboxyl group-containing acrylic rubber, and is in the range of 5.0 × 10 -3 to 1.5 × 10 −2 mephr.
The amount of the ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation using the ethanol aqueous solution containing 75% by volume of ethanol and 25% by volume of water is 3.0 to 8.0% by weight.
Provided is a carboxyl group-containing acrylic rubber in which the amount of change in the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is in the range of 0.2 × 10 -3 to 1.2 × 10 -3 mephr. To.
　本発明のカルボキシル基含有アクリルゴムにおいて、前記カルボキシル基含有単量体単位が、ブテンジオン酸モノエステル単量体単位であることが好ましい。
　本発明のカルボキシル基含有アクリルゴムにおいて、前記カルボキシル基含有単量体単位が、フマル酸モノエステル単量体単位であることが好ましい。
　本発明のカルボキシル基含有アクリルゴムにおいて、前記エタノール水溶液抽出量が４．０～６．５重量％であることが好ましい。
　本発明のカルボキシル基含有アクリルゴムにおいて、前記エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量が０．５×１０－３～０．８×１０－３ｍｅｐｈｒの範囲であることが好ましい。 In the carboxyl group-containing acrylic rubber of the present invention, it is preferable that the carboxyl group-containing monomer unit is a butendionic acid monoester monomer unit.
In the carboxyl group-containing acrylic rubber of the present invention, it is preferable that the carboxyl group-containing monomer unit is a fumaric acid monoester monomer unit.
In the carboxyl group-containing acrylic rubber of the present invention, the extraction amount of the aqueous ethanol solution is preferably 4.0 to 6.5% by weight.
In the carboxyl group-containing acrylic rubber of the present invention, the amount of change in the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is in the range of 0.5 × 10 -3 to 0.8 × 10 -3 mephr. It is preferable to have.
　また、本発明によれば、上記に記載のカルボキシル基含有アクリルゴムを含むゴム成分と、架橋剤とを含むゴム組成物が提供される。
　さらに、本発明によれば、上記に記載のゴム組成物を架橋してなるゴム架橋物が提供される。 Further, according to the present invention, there is provided a rubber composition containing the above-mentioned carboxyl group-containing acrylic rubber-containing rubber component and a cross-linking agent.
Further, according to the present invention, there is provided a rubber crosslinked product obtained by cross-linking the rubber composition described above.
　本発明によれば、加工性に優れ、かつ、耐圧縮永久歪み性に優れたゴム架橋物を与えることのできるカルボキシル基含有アクリルゴムを提供することができる。 According to the present invention, it is possible to provide a carboxyl group-containing acrylic rubber capable of giving a rubber crosslinked product having excellent processability and excellent compression set resistance.
＜カルボキシル基含有アクリルゴム＞
　本発明のカルボキシル基含有アクリルゴムは、（メタ）アクリル酸エステル単量体単位およびカルボキシル基含有単量体単位を含有し、
　カルボキシル基含有量が、前記カルボキシル基含有アクリルゴム１００ｇ当たりのカルボキシル基のモル数で、５．０×１０－３～１．５×１０－２ｍｅｐｈｒの範囲であり、
　エタノールを７５体積％および水を２５体積％の割合で含有するエタノール水溶液を用いたエタノール水溶液抽出操作により抽出される、エタノール水溶液抽出量が３．０～８．０重量％であり、
　前記エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量が０．２×１０－３～１．２×１０－３ｍｅｐｈｒの範囲であるものである。 <Acrylic rubber containing carboxyl group>
The carboxyl group-containing acrylic rubber of the present invention contains a (meth) acrylic acid ester monomer unit and a carboxyl group-containing monomer unit.
The carboxyl group content is the number of moles of carboxyl groups per 100 g of the carboxyl group-containing acrylic rubber, and is in the range of 5.0 × 10 -3 to 1.5 × 10 −2 mephr.
The amount of the ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation using the ethanol aqueous solution containing 75% by volume of ethanol and 25% by volume of water is 3.0 to 8.0% by weight.
The amount of change in the carboxyl group content when the extraction is performed by the ethanol aqueous solution extraction operation is in the range of 0.2 × 10 -3 to 1.2 × 10 -3 mephr.
　本発明のカルボキシル基含有アクリルゴムは、分子中に、主成分（本発明においては、ゴム全単量体単位中５０重量％以上有するものを言う。）としての（メタ）アクリル酸エステル単量体〔アクリル酸エステル単量体および／またはメタクリル酸エステル単量体の意。以下、（メタ）アクリル酸メチルなど同様。〕単位と、カルボキシル基含有単量体単位とを含有するゴム状の重合体である。 The carboxyl group-containing acrylic rubber of the present invention is a (meth) acrylic acid ester monomer as a main component (in the present invention, a rubber having 50% by weight or more in the total rubber monomer unit) in the molecule. [Acrylic acid ester monomer and / or methacrylic acid ester monomer. Hereinafter, the same applies to methyl (meth) acrylate and the like. ] A rubber-like polymer containing a unit and a carboxyl group-containing monomer unit.
　（メタ）アクリル酸エステル単量体単位を形成する（メタ）アクリル酸エステル単量体としては、特に限定されないが、たとえば、（メタ）アクリル酸アルキルエステル単量体、および（メタ）アクリル酸アルコキシアルキルエステル単量体などを挙げることができる。 The (meth) acrylic acid ester monomer forming the (meth) acrylic acid ester monomer unit is not particularly limited, and is, for example, a (meth) acrylic acid alkyl ester monomer and a (meth) acrylic acid alkoxy. Alkoxy ester monomers and the like can be mentioned.
　（メタ）アクリル酸アルキルエステル単量体としては、特に限定されないが、炭素数１～１２のアルカノールと（メタ）アクリル酸とのエステル（炭素数１～１２のアルキル基を有する（メタ）アクリル酸エステル）が好ましく、炭素数１～８のアルカノールと（メタ）アクリル酸とのエステル（炭素数１～８のアルキル基を有する（メタ）アクリル酸エステル）がより好ましく、炭素数２～６のアルカノールと（メタ）アクリル酸とのエステル（炭素数２～６のアルキル基を有する（メタ）アクリル酸エステル）がさらに好ましい。 The (meth) acrylic acid alkyl ester monomer is not particularly limited, but is an ester of an alkanol having 1 to 12 carbon atoms and a (meth) acrylic acid (a (meth) acrylic acid having an alkyl group having 1 to 12 carbon atoms. Esters) are preferable, and esters of alkanols having 1 to 8 carbon atoms and (meth) acrylic acid ((meth) acrylic acid esters having an alkyl group having 1 to 8 carbon atoms) are more preferable, and alkanols having 2 to 6 carbon atoms are more preferable. And an ester of (meth) acrylic acid (a (meth) acrylic acid ester having an alkyl group having 2 to 6 carbon atoms) is more preferable.
　（メタ）アクリル酸アルキルエステル単量体の具体例としては、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸ｎ－プロピル、（メタ）アクリル酸イソプロピル、（メタ）アクリル酸ｎ－ブチル、（メタ）アクリル酸イソブチル、（メタ）アクリル酸ｎ－ヘキシル、（メタ）アクリル酸２－エチルヘキシル、および（メタ）アクリル酸シクロヘキシルなどが挙げられる。これらの中でも、（メタ）アクリル酸エチル、および（メタ）アクリル酸ｎ－ブチルが好ましく、アクリル酸エチル、およびアクリル酸ｎ－ブチルがより好ましい。これらは１種単独で、または２種以上を併せて使用することができる。 Specific examples of the (meth) acrylic acid alkyl ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and (meth) acrylic. Examples thereof include n-butyl acid, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylate. Among these, ethyl (meth) acrylate and n-butyl (meth) acrylate are preferable, and ethyl acrylate and n-butyl acrylate are more preferable. These can be used alone or in combination of two or more.
　（メタ）アクリル酸アルコキシアルキルエステル単量体としては、特に限定されないが、炭素数２～１２のアルコキシアルキルアルコールと（メタ）アクリル酸とのエステル（炭素数２～１２のアルコキシアルキル基を有する（メタ）アクリル酸エステル）が好ましく、炭素数２～８のアルコキシアルキルアルコールと（メタ）アクリル酸とのエステル（炭素数２～８のアルコキシアルキル基を有する（メタ）アクリル酸エステル）がより好ましく、炭素数２～６のアルコキシアルキルアルコールと（メタ）アクリル酸とのエステル（炭素数２～６のアルコキシアルキル基を有する（メタ）アクリル酸エステル）がさらに好ましい。 The (meth) acrylic acid alkoxyalkyl ester monomer is not particularly limited, but has an ester of an alkoxyalkyl alcohol having 2 to 12 carbon atoms and an (meth) acrylic acid (having an alkoxyalkyl group having 2 to 12 carbon atoms). (Meta) acrylic acid ester) is preferable, and an ester of an alkoxyalkyl alcohol having 2 to 8 carbon atoms and (meth) acrylic acid (a (meth) acrylic acid ester having an alkoxyalkyl group having 2 to 8 carbon atoms) is more preferable. An ester of an alkoxyalkyl alcohol having 2 to 6 carbon atoms and a (meth) acrylic acid (a (meth) acrylic acid ester having an alkoxyalkyl group having 2 to 6 carbon atoms) is more preferable.
　（メタ）アクリル酸アルコキシアルキルエステル単量体の具体例としては、（メタ）アクリル酸メトキシメチル、（メタ）アクリル酸エトキシメチル、（メタ）アクリル酸２－メトキシエチル、（メタ）アクリル酸２－エトキシエチル、（メタ）アクリル酸２－プロポキシエチル、（メタ）アクリル酸２－ブトキシエチル、（メタ）アクリル酸３－メトキシプロピル、および（メタ）アクリル酸４－メトキシブチルなどが挙げられる。これらの中でも、（メタ）アクリル酸２－エトキシエチル、および（メタ）アクリル酸２－メトキシエチルが好ましく、アクリル酸２－エトキシエチル、およびアクリル酸２－メトキシエチルが特に好ましい。これらは１種単独で、または２種以上を併せて使用することができる。 Specific examples of the (meth) acrylic acid alkoxyalkyl ester monomer include (meth) acrylic acid methoxymethyl, (meth) acrylic acid ethoxymethyl, (meth) acrylic acid 2-methoxyethyl, and (meth) acrylic acid 2-. Examples thereof include ethoxyethyl, 2-propoxyethyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, and 4-methoxybutyl (meth) acrylate. Among these, 2-ethoxyethyl (meth) acrylate and 2-methoxyethyl (meth) acrylate are preferable, and 2-ethoxyethyl acrylate and 2-methoxyethyl acrylate are particularly preferable. These can be used alone or in combination of two or more.
　本発明のカルボキシル基含有アクリルゴムを構成する全単量体単位中における、（メタ）アクリル酸エステル単量体単位の含有量は、好ましくは７０～９９．９重量％であり、より好ましくは８０～９９．５重量％、さらに好ましくは９０～９９重量％、特に好ましくは９７～９９重量％である。（メタ）アクリル酸エステル単量体単位の含有量を上記範囲とすることにより、得られるゴム架橋物の耐候性、耐熱性、および耐油性を充分なものとすることができる。 The content of the (meth) acrylic acid ester monomer unit in all the monomer units constituting the carboxyl group-containing acrylic rubber of the present invention is preferably 70 to 99.9% by weight, more preferably 80. It is 99.5% by weight, more preferably 90 to 99% by weight, and particularly preferably 97 to 99% by weight. By setting the content of the (meth) acrylic acid ester monomer unit in the above range, the weather resistance, heat resistance, and oil resistance of the obtained rubber crosslinked product can be made sufficient.
　なお、本発明のカルボキシル基含有アクリルゴムにおいては、（メタ）アクリル酸エステル単量体単位として、（メタ）アクリル酸アルキルエステル単量体単位３０～１００重量％、および（メタ）アクリル酸アルコキシアルキルエステル単量体単位７０～０重量％からなるものとすることが好ましく、（メタ）アクリル酸アルキルエステル単量体単位９０～１００重量％、および（メタ）アクリル酸アルコキシアルキルエステル単量体単位１０～０重量％からなるものとすることがより好ましく、（メタ）アクリル酸アルキルエステル単量体単位１００重量％、および（メタ）アクリル酸アルコキシアルキルエステル単量体単位０重量％からなるものとすることがさらに好ましい。（メタ）アクリル酸アルキルエステル単量体単位および（メタ）アクリル酸アルコキシアルキルエステル単量体単位の含有割合を上記範囲とすることにより、得られるゴム架橋物の耐油性および耐寒性を充分なものとすることができる。 In the carboxyl group-containing acrylic rubber of the present invention, the (meth) acrylic acid ester monomer unit is 30 to 100% by weight of the (meth) acrylic acid alkyl ester monomer unit, and the (meth) acrylic acid alkoxyalkyl. It is preferably composed of 70 to 0% by weight of the ester monomer unit, 90 to 100% by weight of the (meth) acrylic acid alkyl ester monomer unit, and 10 of the (meth) acrylic acid alkoxyalkyl ester monomer unit. It is more preferably composed of ~ 0% by weight, and it is composed of 100% by weight of the (meth) acrylic acid alkyl ester monomer unit and 0% by weight of the (meth) acrylic acid alkoxyalkyl ester monomer unit. Is even more preferable. By setting the content ratio of the (meth) acrylic acid alkyl ester monomer unit and the (meth) acrylic acid alkoxyalkyl ester monomer unit within the above range, the obtained rubber crosslinked product has sufficient oil resistance and cold resistance. Can be.
　カルボキシル基含有単量体単位を形成するカルボキシル基含有単量体としては、特に限定されないが、たとえば、α，β－エチレン性不飽和モノカルボン酸、α，β－エチレン性不飽和ジカルボン酸、およびα，β－エチレン性不飽和ジカルボン酸モノエステルなどが挙げられる。カルボキシル基含有単量体単位を含有することにより、アクリルゴムを、カルボキシル基を架橋点として持つカルボキシル基含有アクリルゴムとすることができ、これにより、ゴム架橋物とした場合における、耐圧縮永久歪み性を適切に高めることができる。 The carboxyl group-containing monomer forming the carboxyl group-containing monomer unit is not particularly limited, and is, for example, α, β-ethylenic unsaturated monocarboxylic acid, α, β-ethylenic unsaturated dicarboxylic acid, and Examples thereof include α and β-ethylenic unsaturated dicarboxylic acid monoesters. By containing the carboxyl group-containing monomer unit, the acrylic rubber can be made into a carboxyl group-containing acrylic rubber having a carboxyl group as a cross-linking point, whereby the compression-resistant permanent strain in the case of a rubber cross-linked product can be obtained. The sex can be appropriately enhanced.
　α，β－エチレン性不飽和モノカルボン酸としては、特に限定されないが、炭素数３～１２のα，β－エチレン性不飽和モノカルボン酸が好ましく、その具体例としては、アクリル酸、メタクリル酸、α－エチルアクリル酸、クロトン酸、およびケイ皮酸などが挙げられる。
　α，β－エチレン性不飽和ジカルボン酸としては、特に限定されないが、炭素数４～１２のα，β－エチレン性不飽和ジカルボン酸が好ましく、その具体例としては、フマル酸、マレイン酸などのブテンジオン酸；イタコン酸；シトラコン酸；クロロマレイン酸；などが挙げられる。
　α，β－エチレン性不飽和ジカルボン酸モノエステルとしては、特に限定されないが、炭素数４～１２のα，β－エチレン性不飽和ジカルボン酸とアルカノールとのモノエステルが好ましく、炭素数４～６のα，β－エチレン性不飽和ジカルボン酸とアルカノールとのモノエステルがより好ましく、炭素数４のブテンジオン酸とアルカノールとのモノエステルがさらに好ましい。すなわち、ブテンジオン酸モノエステルが好ましい。なお、アルカノールとしては、炭素数１～１２のものが好ましく、炭素数２～８のものがより好ましく、炭素数２～６のものがさらに好ましい。α，β－エチレン性不飽和ジカルボン酸モノエステルの具体例としては、フマル酸モノメチル、フマル酸モノエチル、フマル酸モノｎ－ブチル、マレイン酸モノメチル、マレイン酸モノエチル、マレイン酸モノｎ－ブチルなどのブテンジオン酸モノ鎖状アルキルエステル；フマル酸モノシクロペンチル、フマル酸モノシクロヘキシル、フマル酸モノシクロヘキセニル、マレイン酸モノシクロペンチル、マレイン酸モノシクロヘキシル、マレイン酸モノシクロヘキセニルなどの脂環構造を有するブテンジオン酸モノエステル；イタコン酸モノメチル、イタコン酸モノエチル、イタコン酸モノｎ－ブチル、イタコン酸モノシクロヘキシルなどのイタコン酸モノエステル；などが挙げられる。これらの中でも、フマル酸モノエステルが好ましく、フマル酸モノｎ－ブチルがより好ましい。これらのα，β－エチレン性不飽和カルボン酸単量体は、１種単独で、または２種以上を併せて使用することができる。なお、上記単量体のうち、ジカルボン酸には、無水物として存在しているものも含まれる。 The α, β-ethylenically unsaturated monocarboxylic acid is not particularly limited, but α, β-ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms is preferable, and specific examples thereof include acrylic acid and methacrylic acid. , Α-Ethylacrylic acid, crotonic acid, cinnamic acid and the like.
The α, β-ethylenic unsaturated dicarboxylic acid is not particularly limited, but α, β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms is preferable, and specific examples thereof include fumaric acid and maleic acid. Butendioic acid; itaconic acid; citraconic acid; chloromaleic acid; and the like.
The α, β-ethylenically unsaturated dicarboxylic acid monoester is not particularly limited, but a monoester of α, β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms and alkanol is preferable, and 4 to 6 carbon atoms are preferable. The monoester of α, β-ethylenically unsaturated dicarboxylic acid and alkanol is more preferable, and the monoester of butendionic acid having 4 carbon atoms and alkanol is even more preferable. That is, butendionic acid monoester is preferable. As the alkanol, those having 1 to 12 carbon atoms are preferable, those having 2 to 8 carbon atoms are more preferable, and those having 2 to 6 carbon atoms are further preferable. Specific examples of the α, β-ethylenic unsaturated dicarboxylic acid monoester include butendione such as monomethyl fumarate, monoethyl fumarate, mono n-butyl fumarate, monomethyl maleate, monoethyl maleate, and mono n-butyl maleate. Acid monochain alkyl ester; butendionic acid monoester having an alicyclic structure such as monocyclopentyl fumarate, monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate, monocyclohexenyl maleate; Examples thereof include monomethyl itaconate, monoethyl itaconate, monon-butyl itaconate, monoester of itaconate such as monocyclohexyl itaconate; and the like. Among these, fumaric acid monoester is preferable, and fumaric acid mono-n-butyl is more preferable. These α, β-ethylenically unsaturated carboxylic acid monomers can be used alone or in combination of two or more. Among the above-mentioned monomers, the dicarboxylic acid includes those existing as an anhydride.
　本発明のカルボキシル基含有アクリルゴムを構成する全単量体単位中における、カルボキシル基含有単量体単位の含有量は、カルボキシル基含有アクリルゴム中におけるカルボキシル基含有量が上記した範囲となる量とすればよいが、好ましくは０．０１重量％以上であり、より好ましくは０．０１～２０重量％、さらに好ましくは０．１～１０重量％、さらにより好ましくは０．５～５重量％、特に好ましくは１～３重量％である。 The content of the carboxyl group-containing monomer unit in all the monomer units constituting the carboxyl group-containing acrylic rubber of the present invention is such that the carboxyl group content in the carboxyl group-containing acrylic rubber is in the above range. However, it is preferably 0.01% by weight or more, more preferably 0.01 to 20% by weight, still more preferably 0.1 to 10% by weight, still more preferably 0.5 to 5% by weight. Particularly preferably, it is 1 to 3% by weight.
　また、本発明のカルボキシル基含有アクリルゴムは、（メタ）アクリル酸エステル単量体単位およびカルボキシル基含有単量体単位に加えて、これらと共重合可能な他の単量体の単位を有していてもよい。このような共重合可能な他の単量体としては、特に限定されないが、エポキシ基を有する単量体、ハロゲン原子を有する単量体、ジエン単量体、芳香族ビニル単量体、α，β－エチレン性不飽和ニトリル単量体、アクリルアミド系単量体、α，β－エチレン性不飽和ジカルボン酸ジエステル単量体、その他のオレフィン系単量体などが挙げられる。 Further, the carboxyl group-containing acrylic rubber of the present invention has a (meth) acrylic acid ester monomer unit and a carboxyl group-containing monomer unit, as well as other monomer units copolymerizable with these. May be. The other such copolymerizable monomer is not particularly limited, but is a monomer having an epoxy group, a monomer having a halogen atom, a diene monomer, an aromatic vinyl monomer, α, Examples thereof include β-ethylenic unsaturated nitrile monomer, acrylamide-based monomer, α, β-ethylenic unsaturated dicarboxylic acid diester monomer, and other olefin-based monomers.
　エポキシ基を有する単量体としては、特に限定されないが、たとえば、（メタ）アクリル酸グリシジルなどのエポキシ基含有（メタ）アクリル酸エステル；アリルグリシジルエーテルおよびビニルグリシジルエーテルなどのエポキシ基含有エーテル；などが挙げられる。 The monomer having an epoxy group is not particularly limited, and for example, an epoxy group-containing (meth) acrylic acid ester such as glycidyl (meth) acrylate; an epoxy group-containing ether such as allyl glycidyl ether and vinyl glycidyl ether; and the like. Can be mentioned.
　ハロゲン原子を有する単量体としては、特に限定されないが、たとえば、ハロゲン含有飽和カルボン酸の不飽和アルコールエステル、（メタ）アクリル酸ハロアルキルエステル、（メタ）アクリル酸ハロアシロキシアルキルエステル、（メタ）アクリル酸（ハロアセチルカルバモイルオキシ）アルキルエステル、ハロゲン含有不飽和エーテル、ハロゲン含有不飽和ケトン、ハロメチル基含有芳香族ビニル化合物、ハロゲン含有不飽和アミド、およびハロアセチル基含有不飽和単量体などが挙げられる。なお、ハロゲン原子を有する単量体としては、ハロゲン原子として、塩素原子を含有するものであることが好ましい。 The monomer having a halogen atom is not particularly limited, and 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, or a (meth) acrylic. Examples thereof include acid (haloacetylcarbamoyloxy) alkyl esters, halogen-containing unsaturated ethers, halogen-containing unsaturated ketones, halomethyl group-containing aromatic vinyl compounds, halogen-containing unsaturated amides, and haloacetyl group-containing unsaturated monomers. The monomer having a halogen atom preferably contains a chlorine atom as the halogen atom.
　ハロゲン含有飽和カルボン酸の不飽和アルコールエステルの具体例としては、クロロ酢酸ビニル、２－クロロプロピオン酸ビニル、およびクロロ酢酸アリルなどが挙げられる。
　（メタ）アクリル酸ハロアルキルエステルの具体例としては、（メタ）アクリル酸クロロメチル、（メタ）アクリル酸１－クロロエチル、（メタ）アクリル酸２－クロロエチル、（メタ）アクリル酸１，２－ジクロロエチル、（メタ）アクリル酸２－クロロプロピル、（メタ）アクリル酸３－クロロプロピル、および（メタ）アクリル酸２，３－ジクロロプロピルなどが挙げられる。
　（メタ）アクリル酸ハロアシロキシアルキルエステルの具体例としては、（メタ）アクリル酸２－（クロロアセトキシ）エチル、（メタ）アクリル酸２－（クロロアセトキシ）プロピル、（メタ）アクリル酸３－（クロロアセトキシ）プロピル、および（メタ）アクリル酸３－（ヒドロキシクロロアセトキシ）プロピルなどが挙げられる。
　（メタ）アクリル酸（ハロアセチルカルバモイルオキシ）アルキルエステルの具体例としては、（メタ）アクリル酸２－（クロロアセチルカルバモイルオキシ）エチル、および（メタ）アクリル酸３－（クロロアセチルカルバモイルオキシ）プロピルなどが挙げられる。 Specific examples of the unsaturated alcohol ester of the halogen-containing saturated carboxylic acid include vinyl chloroacetate, vinyl 2-chloropropionate, and allyl chloroacetic acid.
Specific examples of the (meth) acrylic acid haloalkyl ester include (meth) acrylic acid chloromethyl, (meth) acrylic acid 1-chloroethyl, (meth) acrylic acid 2-chloroethyl, and (meth) acrylic acid 1,2-dichloroethyl. , 2-chloropropyl (meth) acrylic acid, 3-chloropropyl (meth) acrylic acid, and 2,3-dichloropropyl (meth) acrylic acid.
Specific 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- (chloro). Examples thereof include acetoxy) propyl and 3- (hydroxychloroacetoxy) propyl (meth) acrylate.
Specific examples of the (meth) acrylic acid (haloacetylcarbamoyloxy) alkyl ester include (meth) acrylic acid 2- (chloroacetylcarbamoyloxy) ethyl and (meth) acrylic acid 3- (chloroacetylcarbamoyloxy) propyl. Can be mentioned.
　ハロゲン含有不飽和エーテルの具体例としては、クロロメチルビニルエーテル、２－クロロエチルビニルエーテル、３－クロロプロピルビニルエーテル、２－クロロエチルアリルエーテル、および３－クロロプロピルアリルエーテルなどが挙げられる。
　ハロゲン含有不飽和ケトンの具体例としては、２－クロロエチルビニルケトン、３－クロロプロピルビニルケトン、および２－クロロエチルアリルケトンなどが挙げられる。
　ハロメチル基含有芳香族ビニル化合物の具体例としては、ｐ－クロロメチルスチレン、ｍ－クロロメチルスチレン、ｏ－クロロメチルスチレン、およびｐ－クロロメチル－α－メチルスチレンなどが挙げられる。 Specific 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.
Specific examples of the halogen-containing unsaturated ketone include 2-chloroethyl vinyl ketone, 3-chloropropyl vinyl ketone, 2-chloroethyl allyl ketone and the like.
Specific examples of the halomethyl group-containing aromatic vinyl compound include p-chloromethylstyrene, m-chloromethylstyrene, o-chloromethylstyrene, and p-chloromethyl-α-methylstyrene.
　ハロゲン含有不飽和アミドの具体例としては、Ｎ－クロロメチル（メタ）アクリルアミドなどが挙げられる。
　ハロアセチル基含有不飽和単量体の具体例としては、３－（ヒドロキシクロロアセトキシ）プロピルアリルエーテル、ｐ－ビニルベンジルクロロ酢酸エステルなどが挙げられる。 Specific examples of the halogen-containing unsaturated amide include N-chloromethyl (meth) acrylamide.
Specific examples of the haloacetyl group-containing unsaturated monomer include 3- (hydroxychloroacetoxy) propyl allyl ether and p-vinylbenzylchloroacetic acid ester.
　ジエン単量体としては、共役ジエン単量体、非共役ジエン単量体が挙げられる。
　共役ジエン単量体の具体例としては、１，３－ブタジエン、イソプレン、およびピペリレンなどが挙げられる。
　非共役ジエン単量体の具体例としては、エチリデンノルボルネン、ジシクロペンタジエン、（メタ）アクリル酸ジシクロペンタジエニル、および（メタ）アクリル酸２－ジシクロペンタジエニルエチルなどが挙げられる。 Examples of the diene monomer include a conjugated diene monomer and a non-conjugated diene monomer.
Specific examples of the conjugated diene monomer include 1,3-butadiene, isoprene, piperylene and the like.
Specific examples of the non-conjugated diene monomer include ethylidene norbornene, dicyclopentadiene, dicyclopentadienyl (meth) acrylate, and 2-dicyclopentadienyl ethyl (meth) acrylate.
　芳香族ビニル単量体としては、スチレン、α－メチルスチレン、ジビニルベンゼンなどが挙げられる。
　α，β－エチレン性不飽和ニトリル単量体としては、アクリロニトリル、メタクリロニトリルなどが挙げられる。
　アクリルアミド系単量体としては、アクリルアミド、メタクリルアミドなどが挙げられる。
　α，β－エチレン性不飽和ジカルボン酸ジエステル単量体としては、マレイン酸ジメチル、マレイン酸ジｎ－ブチルなどのマレイン酸ジアルキルエステルであってアルキル基の炭素数が１～１８のもの；フマル酸ジメチル、フマル酸ジｎ－ブチルなどのフマル酸ジアルキルエステルであってアルキル基の炭素数が１～１８のもの；マレイン酸ジシクロペンチル、マレイン酸ジシクロヘキシルなどのマレイン酸ジシクロアルキルエステルであってシクロアルキル基の炭素数が４～１６のもの；フマル酸ジシクロペンチル、フマル酸ジシクロヘキシルなどのフマル酸ジシクロアルキルエステルであってシクロアルキル基の炭素数が４～１６のもの；イタコン酸ジメチル、イタコン酸ジｎ－ブチルなどのイタコン酸ジアルキルエステルであってアルキル基の炭素数が１～１８のもの：イタコン酸ジシクロヘキシルなどのイタコン酸ジシクロアルキルエステルであってシクロアルキル基の炭素数が４～１６のもの；などが挙げられる。
　その他のオレフィン系単量体としては、エチレン、プロピレン、塩化ビニル、塩化ビニリデン、酢酸ビニル、エチルビニルエーテル、ブチルビニルエーテルなどが挙げられる。 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.
The α, β-ethylenic unsaturated dicarboxylic acid diester monomer is a maleic acid dialkyl ester such as dimethyl maleate or din-butyl maleate having an alkyl group having 1 to 18 carbon atoms; fumaric acid. A fumaric acid dialkyl ester such as dimethyl or din-butyl fumarate having an alkyl group having 1 to 18 carbon atoms; a dicyclopentyl maleate such as dicyclopentyl maleate or dicyclohexyl maleate and a cycloalkyl ester. A group having 4 to 16 carbon atoms; a fumaric acid dicycloalkyl ester such as dicyclopentyl fumarate and dicyclohexyl fumarate having a cycloalkyl group having 4 to 16 carbon atoms; dimethyl itaconate, diitaconic acid Itaconic acid dialkyl ester such as n-butyl having an alkyl group having 1 to 18 carbon atoms: an itaconic acid dicycloalkyl ester such as itaconic acid dicyclohexyl having a cycloalkyl group having 4 to 16 carbon atoms. ; And so on.
Examples of other olefin-based monomers include ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, ethyl vinyl ether, and butyl vinyl ether.
　共重合可能な他の単量体は、１種単独で、または２種以上を併せて使用することができる。本発明のカルボキシル基含有アクリルゴムを構成する単量体単位中における、これら共重合可能な他の単量体の単位の含有量は、好ましくは２９．９重量％以下であり、より好ましくは１５重量％以下、さらに好ましくは９重量％以下、特に好ましくは４．５重量％以下である。 Other copolymerizable monomers can be used alone or in combination of two or more. The content of the units of these other copolymerizable monomers in the monomer unit constituting the carboxyl group-containing acrylic rubber of the present invention is preferably 29.9% by weight or less, more preferably 15. It is 0% by weight or less, more preferably 9% by weight or less, and particularly preferably 4.5% by weight or less.
　なお、本発明のカルボキシル基含有アクリルゴムを、共重合可能な他の単量体の単位を含有するものとする場合には、その含有量は、上記範囲とすればよいが、なかでも、エチレン単位を有するものとする場合には、本発明のカルボキシル基含有アクリルゴムを構成する単量体単位中における、エチレン単位の含有量は、９重量％以下とすることが好ましく、４．５重量％以下とすることがより好ましい。同様に、本発明のカルボキシル基含有アクリルゴムを、アクリロニトリル単位や、メタクリロニトリル単位を有するものとする場合にも、アクリロニトリル単位およびメタクリロニトリル単位の合計の含有量を、９重量％以下とすることが好ましく、４．５重量％以下とすることがより好ましい。 When the carboxyl group-containing acrylic rubber of the present invention contains a unit of another copolymerizable monomer, the content thereof may be in the above range, but among them, ethylene. When having a unit, the content of the ethylene unit in the monomer unit constituting the carboxyl group-containing acrylic rubber of the present invention is preferably 9% by weight or less, preferably 4.5% by weight. The following is more preferable. Similarly, when the carboxyl group-containing acrylic rubber of the present invention has an acrylonitrile unit or a methacrylonitrile unit, the total content of the acrylonitrile unit and the methacrylonitrile unit shall be 9% by weight or less. It is preferably 4.5% by weight or less, and more preferably 4.5% by weight or less.
　また、本発明のカルボキシル基含有アクリルゴムは、カルボキシル基含有量が、カルボキシル基含有アクリルゴム１００ｇ当たりのカルボキシル基のモル数で、５．０×１０－３～１．５×１０－２ｍｅｐｈｒ（ｍｏｌａｒ　ｅｑｕｉｖａｌｅｎｔ　ｐｅｒ　ｈｕｎｄｒｅｄ　ｒｕｂｂｅｒ）の範囲にあるものである。本発明によれば、カルボキシル基含有アクリルゴム中におけるカルボキシル基含有量を上記範囲とし、かつ、後述する、エタノール水溶液抽出操作により抽出される、エタノール水溶液抽出量を３．０～８．０重量％の範囲、および、エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量を０．２×１０－３～１．２×１０－３ｍｅｐｈｒの範囲とすることにより、カルボキシル基含有アクリルゴムを加工性に優れ、かつ、ゴム架橋物とした際における耐圧縮永久歪み性に優れたものとすることができるものである。 Further, the carboxyl group-containing acrylic rubber of the present invention has a carboxyl group content of 5.0 × 10 -3 to 1.5 × 10 -2 mephr (the number of moles of carboxyl groups per 100 g of the carboxyl group-containing acrylic rubber). It is in the range of molar equivalent per undred rubber). According to the present invention, the carboxyl group content in the carboxyl group-containing acrylic rubber is within the above range, and the ethanol aqueous solution extraction amount extracted by the ethanol aqueous solution extraction operation described later is 3.0 to 8.0% by weight. And the amount of change in the carboxyl group content when extracting by the ethanol aqueous solution extraction operation is in the range of 0.2 × 10 -3 to 1.2 × 10 -3 mephr. It is possible to make the contained acrylic rubber excellent in processability and excellent compression resistance and permanent strain resistance when it is made into a rubber crosslinked product.
　本発明のカルボキシル基含有アクリルゴムのカルボキシル基含有量は、５．０×１０－３～１．５×１０－２ｍｅｐｈｒの範囲であればよいが、好ましくは７．０×１０－３～１．２×１０－２ｍｅｐｈｒ、より好ましくは９．０×１０－３～１．０５×１０－２ｍｅｐｈｒである。カルボキシル基含有量が少なすぎても、また、多すぎても、得られるゴム架橋物は耐圧縮永久歪み性に劣るものとなってしまう。カルボキシル基含有アクリルゴムのカルボキシル基含有量は、たとえば、カルボキシル基含有アクリルゴムをアセトンに溶解し、得られた溶液に水を加えることで測定用の試料とし、測定用の試料に対し、アルコール性ＫＯＨを用いて中和点まで滴定を行い、滴定に使用したアルコール性ＫＯＨの量から求められるモル当量を算出することで、測定することができる。 The carboxyl group content of the carboxyl group-containing acrylic rubber of the present invention may be in the range of 5.0 × 10 -3 to 1.5 × 10 −2 mephr, but is preferably 7.0 × 10 -3 to 1. .2 × 10 -2 mephr, more preferably 9.0 × 10 -3 to 1.05 × 10 -2 mephr. If the carboxyl group content is too low or too high, the obtained rubber crosslinked product will be inferior in compression set resistance. The carboxyl group content of the carboxyl group-containing acrylic rubber is determined by, for example, dissolving the carboxyl group-containing acrylic rubber in acetone and adding water to the obtained solution to prepare a sample for measurement, which is alcoholic with respect to the sample for measurement. It can be measured by performing titration to the neutralization point using KOH and calculating the molar equivalent obtained from the amount of alcoholic KOH used for the titration.
　カルボキシル基含有アクリルゴムのカルボキシル基含有量は、たとえば、カルボキシル基含有アクリルゴム中に含まれるカルボキシル基含有単量体単位の量を調整することで調整することができ、より具体的には、カルボキシル基含有アクリルゴムを得る際に、重合に用いる全単量体中におけるカルボキシル基含有単量体の含有量を調整する方法や、最終的な重合転化率を調整する方法などにより、調整することができる。 The carboxyl group content of the carboxyl group-containing acrylic rubber can be adjusted, for example, by adjusting the amount of the carboxyl group-containing monomer unit contained in the carboxyl group-containing acrylic rubber, and more specifically, the carboxyl group. When the group-containing acrylic rubber is obtained, it can be adjusted by a method of adjusting the content of the carboxyl group-containing monomer in all the monomers used for polymerization, a method of adjusting the final polymerization conversion rate, or the like. can.
　なお、本発明のカルボキシル基含有アクリルゴムは、得られるゴム架橋物の耐圧縮永久歪み性をより優れたものとするという観点より、カルボキシル基含有単量体単位を形成する単量体が、α，β－エチレン性不飽和ジカルボン酸モノエステルであることが好ましく、ブテンジオン酸モノエステルであることがより好ましく、フマル酸モノエステルであることがさらに好ましく、フマル酸モノｎ－ブチルであることが特に好ましい。そのため、上記したカルボキシル基含有量は、主として、α，β－エチレン性不飽和ジカルボン酸モノエステル単量体単位に由来のカルボキシル基の含有量であることが好ましく、ブテンジオン酸モノエステル単量体単位に由来のカルボキシル基の含有量であることがより好ましく、フマル酸モノエステル単量体単位に由来のカルボキシル基の含有量であることがさらに好ましく、フマル酸モノｎ－ブチル単位に由来のカルボキシル基の含有量であることが特に好ましい。 In the carboxyl group-containing acrylic rubber of the present invention, the monomer forming the carboxyl group-containing monomer unit is α from the viewpoint of improving the compression-resistant permanent strain resistance of the obtained rubber cross-linked product. , Β-ethylenically unsaturated dicarboxylic acid monoester is preferable, butendionic acid monoester is more preferable, fumaric acid monoester is further preferable, and fumaric acid monon-butyl is particularly preferable. preferable. Therefore, the above-mentioned carboxyl group content is preferably mainly the content of a carboxyl group derived from the α, β-ethylenic unsaturated dicarboxylic acid monoester monomer unit, and the butendionic acid monoester monomer unit. The content of the carboxyl group derived from the above is more preferable, and the content of the carboxyl group derived from the fumaric acid monoester monomer unit is further preferable, and the content of the carboxyl group derived from the mono n-butyl fumarate unit is more preferable. The content of is particularly preferable.
　また、本発明のカルボキシル基含有アクリルゴムは、エタノールを７５体積％および水を２５体積％の割合（温度２５℃における体積割合）で含有するエタノール水溶液を用いたエタノール水溶液抽出操作により抽出される、エタノール水溶液抽出量が３．０～８．０重量％の範囲である。エタノール水溶液抽出量は、好ましくは４．０～６．５重量％であり、より好ましくは４．４～６．０重量％である。エタノール水溶液抽出操作により抽出される成分は、本発明のカルボキシル基含有アクリルゴム中に含有される比較的低分子量である重合体成分であり、通常、分子量が５，０００以上であり、かつ、エタノール水溶液で抽出される程度の比較的分子量の低い成分である。本発明においては、このようなエタノール水溶液抽出操作により抽出される成分の量、すなわち、比較的低分子量である重合体成分の量を、上記範囲とすることにより、このような比較的低分子量である重合体成分の作用により、優れた加工性を実現できるものである。エタノール水溶液抽出量が少なすぎると、カルボキシル基含有アクリルゴムは加工性に劣るものとなってしまい、一方、エタノール水溶液抽出量が多すぎると、ゴム架橋物とした場合に、耐圧縮永久歪み性に劣るものとなってしまう。 Further, the carboxyl group-containing acrylic rubber of the present invention is extracted by an ethanol aqueous solution extraction operation using an ethanol aqueous solution containing 75% by volume of ethanol and 25% by volume of water (volume ratio at a temperature of 25 ° C.). The amount of ethanol aqueous solution extracted is in the range of 3.0 to 8.0% by weight. The amount of the aqueous ethanol solution extracted is preferably 4.0 to 6.5% by weight, more preferably 4.4 to 6.0% by weight. The component extracted by the ethanol aqueous solution extraction operation is a polymer component having a relatively low molecular weight contained in the carboxyl group-containing acrylic rubber of the present invention, and usually has a molecular weight of 5,000 or more and ethanol. It is a component with a relatively low molecular weight that can be extracted with an aqueous solution. In the present invention, the amount of the component extracted by such an ethanol aqueous solution extraction operation, that is, the amount of the polymer component having a relatively low molecular weight is set within the above range to achieve such a relatively low molecular weight. Excellent processability can be realized by the action of a certain polymer component. If the amount of ethanol aqueous solution extracted is too small, the carboxyl group-containing acrylic rubber will be inferior in processability, while if the amount of ethanol aqueous solution extracted is too large, the rubber cross-linked product will have resistance to compression and permanent strain. It will be inferior.
　なお、本発明において、エタノール水溶液抽出操作は、次のようにして行われる。すなわち、まず、カルボキシル基含有アクリルゴム１．５ｇを、エタノールを７５体積％および水を２５体積％の割合で含有するエタノール水溶液１５０ｍｌに浸漬させ、還流式冷却管を備える加熱装置にて、９０℃以上の温度にて１．５時間加熱するという操作を２回繰り返す（すなわち、１．５時間の加熱操作を２回繰り返す）ことにより行われる。そして、エタノール水溶液抽出操作を行った後のカルボキシル基含有アクリルゴムを乾燥し、その重量を測定することで、エタノール水溶液抽出操作を行った後のカルボキシル基含有アクリルゴムの重量Ｗ１を求め、エタノール水溶液抽出操作を行う前の重量Ｗ０との差分（Ｗ０－Ｗ１）を算出し、エタノール水溶液抽出操作を行う前の重量Ｗ０に対する割合（｛（Ｗ０－Ｗ１）／Ｗ０｝×１００、単位は重量％）を計算することにより、エタノール水溶液抽出量を求めることができる。 In the present invention, the ethanol aqueous solution extraction operation is performed as follows. That is, first, 1.5 g of carboxyl group-containing acrylic rubber is immersed in 150 ml of an ethanol aqueous solution containing 75% by volume of ethanol and 25% by volume of water, and the temperature is 90 ° C. in a heating device equipped with a reflux condenser. It is performed by repeating the operation of heating at the above temperature for 1.5 hours twice (that is, repeating the heating operation for 1.5 hours twice). Then, the carboxyl group-containing acrylic rubber after the ethanol aqueous solution extraction operation is dried, and the weight thereof is measured to obtain the weight W 1 of the carboxyl group-containing acrylic rubber after the ethanol aqueous solution extraction operation, and ethanol is used. Calculate the difference (W 0 -W 1 ) from the weight W 0 before performing the aqueous solution extraction operation, and the ratio to the weight W 0 before performing the ethanol aqueous solution extraction operation ({(W 0 -W 1 ) / W 0 }. By calculating × 100, the unit is% by weight), the amount of ethanol aqueous solution extracted can be obtained.
　カルボキシル基含有アクリルゴムのエタノール水溶液抽出量は、たとえば、後述する、本発明のカルボキシル基含有アクリルゴムの製造方法において、後反応工程開始時の重合転化率を調整する方法や、最終的な重合転化率を調整する方法などにより調整することができるが、これらの方法に特に限定されるものではない。 The amount of the carboxyl group-containing acrylic rubber extracted from the ethanol aqueous solution is, for example, the method for adjusting the polymerization conversion rate at the start of the post-reaction step in the method for producing the carboxyl group-containing acrylic rubber of the present invention, which will be described later, and the final polymerization conversion. It can be adjusted by a method of adjusting the rate or the like, but is not particularly limited to these methods.
　また、本発明のカルボキシル基含有アクリルゴムは、エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量が、カルボキシル基含有アクリルゴム１００ｇ当たりのカルボキシル基のモル数で、０．２×１０－３～１．２×１０－３ｍｅｐｈｒ（ｍｏｌａｒ　ｅｑｕｉｖａｌｅｎｔ　ｐｅｒ　ｈｕｎｄｒｅｄ　ｒｕｂｂｅｒ）の範囲である。エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量は、上記したエタノール水溶液抽出操作を行う前のカルボキシル基含有アクリルゴムのカルボキシル基含有量Ａ０と、上記したエタノール水溶液抽出操作を行った後のカルボキシル基含有アクリルゴムのカルボキシル基含有量Ａ１との差分（Ａ０－Ａ１）であり、エタノール水溶液抽出操作により抽出された成分中のカルボキシル基の含有割合、すなわち、主として、比較的低分子量である重合体成分中のカルボキシル基の含有割合に影響を受けるものである。より具体的には、エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量は、比較的低分子量である重合体成分中のカルボキシル基の含有割合が高いほど、大きくなる傾向にある。 Further, in the carboxyl group-containing acrylic rubber of the present invention, the amount of change in the carboxyl group content when extracted by the ethanol aqueous solution extraction operation is the number of moles of carboxyl groups per 100 g of the carboxyl group-containing acrylic rubber. It is in the range of 2 × 10 -3 to 1.2 × 10 -3 mephr (molar equivalent per undred rubber). The amount of change in the carboxyl group content when extracting by the ethanol aqueous solution extraction operation is the carboxyl group content A0 of the carboxyl group-containing acrylic rubber before the above-mentioned ethanol aqueous solution extraction operation and the above-mentioned ethanol aqueous solution extraction. It is the difference (A 0 −A 1 ) from the carboxyl group content A 1 of the carboxyl group-containing acrylic rubber after the operation, and is the content ratio of the carboxyl group in the components extracted by the ethanol aqueous solution extraction operation, that is, It is mainly affected by the content of carboxyl groups in the polymer component, which has a relatively low molecular weight. More specifically, the amount of change in the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation tends to increase as the content ratio of the carboxyl group in the polymer component having a relatively low molecular weight increases. It is in.
　本発明によれば、カルボキシル基含有アクリルゴムのカルボキシル基含有量およびエタノール水溶液抽出量を上記範囲とし、かつ、エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量を上記範囲とすることにより、優れた加工性を実現しながら、得られるゴム架橋物を耐圧縮永久歪み性に優れたものとすることができるものである。特に、本発明者等が、エタノール水溶液抽出操作により抽出される成分のような比較的低分子量である重合体成分に着目して、鋭意検討を行ったところ、次のような知見を得たものである。すなわち、エタノール水溶液抽出操作により抽出される成分のような比較的低分子量である重合体成分の量を特定の範囲とすることにより、加工性を向上させることができること、その一方で、エタノール水溶液抽出操作により抽出される成分のような比較的低分子量である重合体成分中の中に含まれる、カルボキシル基の量が少なすぎても、また、多すぎても、耐圧縮永久歪み性が低下してしまうことを見出したものであり、このような知見に基づき、本発明を完成させるに至ったものである。特に、本発明者等は、カルボキシル基含有アクリルゴム中において、カルボキシル基は架橋性基として作用することで、耐圧縮永久歪み性の向上に寄与する一方で、エタノール水溶液抽出操作により抽出される成分のような比較的低分子量である重合体成分中の中に含まれる、カルボキシル基の量を特定の範囲に制御することが耐圧縮永久歪み性の向上に資することを見出したものである。 According to the present invention, the carboxyl group content and the ethanol aqueous solution extraction amount of the carboxyl group-containing acrylic rubber are within the above ranges, and the change amount of the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is within the above range. By doing so, it is possible to make the obtained rubber crosslinked product excellent in compression set resistance and permanent strain resistance while realizing excellent processability. In particular, the present inventors have focused on polymer components having a relatively low molecular weight, such as components extracted by an ethanol aqueous solution extraction operation, and conducted a diligent study, and obtained the following findings. Is. That is, the processability can be improved by setting the amount of the polymer component having a relatively low molecular weight such as the component extracted by the ethanol aqueous solution extraction operation within a specific range, and on the other hand, the ethanol aqueous solution extraction can be performed. If the amount of carboxyl groups contained in the polymer component having a relatively low molecular weight such as the component extracted by the operation is too small or too large, the compression set resistance is lowered. It was found that the present invention was completed based on such findings. In particular, the present inventors have contributed to the improvement of compression resistance and permanent strain resistance by acting as a crosslinkable group in the carboxyl group-containing acrylic rubber, while the components extracted by the ethanol aqueous solution extraction operation. It has been found that controlling the amount of carboxyl groups contained in a polymer component having a relatively low molecular weight, such as the above, within a specific range contributes to the improvement of compression resistance and permanent strain resistance.
　カルボキシル基含有アクリルゴムのエタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量は、０．２×１０－３～１．２×１０－３ｍｅｐｈｒの範囲であればよいが、好ましくは０．４×１０－３～１．０×１０－３ｍｅｐｈｒの範囲、さらに好ましくは０．５×１０－３～０．８×１０－３ｍｅｐｈｒの範囲である。カルボキシル基含有アクリルゴムのエタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量が小さすぎると、カルボキシル基含有アクリルゴムは加工性に劣るものとなってしまい、一方、カルボキシル基含有量の変化量が大きすぎると、得られるゴム架橋物が耐圧縮永久歪み性に劣るものとなってしまうことに加え、カルボキシル基含有アクリルゴムは加工性にも劣るものとなってしまう。 The amount of change in the carboxyl group content when the carboxyl group-containing acrylic rubber is extracted by the ethanol aqueous solution extraction operation may be in the range of 0.2 × 10 -3 to 1.2 × 10 -3 mephr. It is preferably in the range of 0.4 × 10 -3 to 1.0 × 10 -3 mephr, and more preferably in the range of 0.5 × 10 -3 to 0.8 × 10 -3 mephr. If the amount of change in the carboxyl group content is too small when the carboxyl group-containing acrylic rubber is extracted by the ethanol aqueous solution extraction operation, the carboxyl group-containing acrylic rubber becomes inferior in processability, while the carboxyl group. If the amount of change in the content is too large, the obtained crosslinked rubber product will be inferior in compressive permanent strain resistance, and the carboxyl group-containing acrylic rubber will also be inferior in processability.
　なお、エタノール水溶液抽出操作を行った後のカルボキシル基含有アクリルゴムのカルボキシル基含有量は、上記と同様にして測定すればよい。 The carboxyl group content of the carboxyl group-containing acrylic rubber after the ethanol aqueous solution extraction operation may be measured in the same manner as described above.
　カルボキシル基含有アクリルゴムのエタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量は、たとえば、後述する、本発明のカルボキシル基含有アクリルゴムの製造方法において、後反応工程開始時の重合転化率を調整する方法や、後反応工程開始時における重合反応系に含まれる全単量体中におけるカルボキシル基含有単量体の割合を調整する方法、最終的な重合転化率を調整する方法などにより調整することができるが、これらの方法に特に限定されるものではない。 The amount of change in the carboxyl group content when the carboxyl group-containing acrylic rubber is extracted by the ethanol aqueous solution extraction operation is, for example, at the start of the post-reaction step in the method for producing the carboxyl group-containing acrylic rubber of the present invention, which will be described later. A method for adjusting the polymerization conversion rate of the above, a method for adjusting the ratio of the carboxyl group-containing monomer in all the monomers contained in the polymerization reaction system at the start of the post-reaction step, and a method for adjusting the final polymerization conversion rate. It can be adjusted by a method or the like, but is not particularly limited to these methods.
　また、カルボキシル基含有量の変化量は、主として、カルボキシル基含有アクリルゴムを形成するカルボキシル基含有単量体単位に由来するものである。そのため、得られるゴム架橋物の耐圧縮永久歪み性をより優れたものとするという観点より、カルボキシル基含有量の変化量は、主として、α，β－エチレン性不飽和ジカルボン酸モノエステルに由来のカルボキシル基の含有量の変化量であることがより好ましく、ブテンジオン酸モノエステル単量体単位に由来のカルボキシル基の含有量の変化量であることがより好ましく、フマル酸モノエステル単量体単位に由来のカルボキシル基の含有量の変化量であることがさらに好ましく、フマル酸モノｎ－ブチル単位に由来のカルボキシル基の含有量の変化量であることが特に好ましい。 Further, the amount of change in the carboxyl group content is mainly derived from the carboxyl group-containing monomer unit forming the carboxyl group-containing acrylic rubber. Therefore, the amount of change in the carboxyl group content is mainly derived from the α, β-ethylenically unsaturated dicarboxylic acid monoester from the viewpoint of improving the compression set resistance of the obtained rubber crosslinked product. It is more preferably the amount of change in the content of the carboxyl group, more preferably the amount of change in the content of the carboxyl group derived from the butenedioic acid monoester monomer unit, and the amount of change in the fumarate monoester monomer unit. It is more preferably the amount of change in the content of the derived carboxyl group, and particularly preferably the amount of change in the content of the carboxyl group derived from the mono-n-butyl fumarate unit.
　なお、カルボキシル基含有アクリルゴムのエタノール水溶液抽出操作により抽出を行った後における、カルボキシル基含有量は、特に限定されないが、好ましくは４．０×１０－３～１．４×１０－２ｍｅｐｈｒであり、より好ましくは６．０×１０－３～１．１×１０－２ｍｅｐｈｒ、さらに好ましくは８．０×１０－３～９．０５×１０－３ｍｅｐｈｒである。カルボキシル基含有アクリルゴムのエタノール水溶液抽出操作により抽出を行った後における、カルボキシル基含有量を上記範囲とすることにより、カルボキシル基含有アクリルゴムの加工性、および、ゴム架橋物とした際における耐圧縮永久歪み性をより高めることができる。 The carboxyl group content after extraction of the carboxyl group-containing acrylic rubber by the ethanol aqueous solution extraction operation is not particularly limited, but is preferably 4.0 × 10 -3 to 1.4 × 10 -2 mepr. Yes, more preferably 6.0 × 10 -3 to 1.1 × 10 -2 mephr, and even more preferably 8.0 × 10 -3 to 9.05 × 10 -3 mephr. By setting the carboxyl group content within the above range after extraction by the ethanol aqueous solution extraction operation of the carboxyl group-containing acrylic rubber, the processability of the carboxyl group-containing acrylic rubber and the compression resistance when the rubber is crosslinked are obtained. Permanent distortion can be further enhanced.
　本発明のカルボキシル基含有アクリルゴムは、ムーニー粘度（ＭＬ１＋４，１００℃）が、１０～１５０の範囲であり、好ましくは２０～１００の範囲、より好ましくは２５～７０の範囲である。ムーニー粘度を上記範囲とすることにより、カルボキシル基含有アクリルゴムの加工性と強度特性を高度にバランスさせることができる。 The carboxyl group-containing acrylic rubber of the present invention has a Mooney viscosity (ML1 + 4,100 ° C.) in the range of 10 to 150, preferably in the range of 20 to 100, and more preferably in the range of 25 to 70. By setting the Mooney viscosity within the above range, the processability and strength characteristics of the carboxyl group-containing acrylic rubber can be highly balanced.
　また、本発明のカルボキシル基含有アクリルゴムの重量平均分子量（Ｍｗ）は、特に限定されないが、機械的強度および加工性を良好なものとするという観点より、好ましくは８００，０００以上であり、より好ましくは８００，０００～２，６００，０００であり、さらに好ましくは９００，０００～２，３００，０００、特に好ましくは１，０００，０００～２，０００，０００である。また、カルボキシル基含有アクリルゴムの分子量分布は、特に限定されないが、Ｍｗ／Ｍｎの値で、好ましくは１．５０～１０．０であり、より好ましくは１．７０～８．００、さらに好ましくは２．００～６．００であり、また、Ｍｚ／Ｍｗの値で、好ましくは１．３０～３．００であり、より好ましくは１．４５～２．７０、さらに好ましくは１．６０～２．５０である。なお、カルボキシル基含有アクリルゴムの重量平均分子量および分子量分布は、たとえば、多角度レーザ光散乱光度計（ＭＡＬＳ）を組み入れたＧＰＣ（Ｇｅｌ　Ｐｅｒｍｅａｔｉｏｎ　Ｃｈｒｏｍａｔｏｇｒａｐｈｙ）装置を用いたＧＰＣ－ＭＡＬＳ法により、絶対分子量および絶対分子量分布として求めることができる。 The weight average molecular weight (Mw) of the carboxyl group-containing acrylic rubber of the present invention is not particularly limited, but is preferably 800,000 or more, more preferably 800,000 or more from the viewpoint of improving mechanical strength and processability. It is preferably 800,000 to 2,600,000, more preferably 900,000 to 2,300,000, and particularly preferably 1,000,000 to 2,000,000. The molecular weight distribution of the carboxyl group-containing acrylic rubber is not particularly limited, but the value of Mw / Mn is preferably 1.50 to 10.0, more preferably 1.70 to 8.00, and further preferably 1.70 to 8.00. It is 2.00 to 6.00, and is preferably a value of Mz / Mw, preferably 1.30 to 3.00, more preferably 1.45 to 2.70, and further preferably 1.60 to 2. It is .50. The weight average molecular weight and molecular weight distribution of the carboxyl group-containing acrylic rubber can be determined by, for example, the absolute molecular weight and the absolute molecular weight by the GPC-MALS method using a GPC (Gel Permeation Chromatography) apparatus incorporating a multi-angle laser light scattering photometric meter (MALS). It can be obtained as an absolute molecular weight distribution.
＜カルボキシル基含有アクリルゴムの製造方法＞
　本発明のカルボキシル基含有アクリルゴムを製造するための方法としては、特に限定されず、任意の方法を採用すればよいが、たとえば、次の方法が好適である。すなわち、
　（メタ）アクリル酸エステル単量体およびカルボキシル基含有単量体を含む、重合に用いる単量体成分を、乳化剤および水とを用いて乳化させることで、単量体乳化液を得る単量体乳化液調製工程と、
　前記単量体乳化液調製工程で調製した単量体乳化液の全量のうち一部に対し、重合開始剤を添加することで、重合反応を開始させる初期重合工程と、
　前記単量体乳化液調製工程で調製した単量体乳化液のうち残部を、重合反応系に連続的あるいは継続的に滴下することで、重合反応を進行させる単量体乳化液滴下工程と、
　前記単量体乳化液の滴下を終了した後、重合反応系に、重合開始剤および／または分子量調整剤を添加して、重合反応を継続する後反応工程と、を含む製造方法が好適である。 <Manufacturing method of carboxyl group-containing acrylic rubber>
The method for producing the carboxyl group-containing acrylic rubber of the present invention is not particularly limited, and any method may be adopted, but for example, the following method is suitable. That is,
A monomer obtained by emulsifying a monomer component used for polymerization, which contains a (meth) acrylic acid ester monomer and a carboxyl group-containing monomer, with an emulsifier and water to obtain a monomer emulsified solution. Emulsification liquid preparation process and
An initial polymerization step of initiating a polymerization reaction by adding a polymerization initiator to a part of the total amount of the monomeric emulsion prepared in the monomer emulsion preparation step.
The monomer emulsification droplet lowering step of advancing the polymerization reaction by continuously or continuously dropping the remainder of the monomer emulsifying liquid prepared in the monomer emulsifying liquid preparation step onto the polymerization reaction system.
A production method including a post-reaction step of adding a polymerization initiator and / or a molecular weight adjusting agent to the polymerization reaction system after completing the dropping of the monomer emulsion to continue the polymerization reaction is preferable. ..
（単量体乳化液調製工程）
　単量体乳化液調製工程は、（メタ）アクリル酸エステル単量体およびカルボキシル基含有単量体を含む、重合に用いる単量体成分を、乳化剤および水とを用いて乳化させることで、単量体乳化液を得る工程である。 (Monomer emulsion preparation process)
In the monomer emulsion preparation step, a monomer component used for polymerization, including a (meth) acrylic acid ester monomer and a carboxyl group-containing monomer, is emulsified with an emulsifier and water. This is a step of obtaining a monomer emulsion.
　単量体乳化液を調製する際に用いる単量体成分としては、上記した各単量体を挙げることができ、好適な単量体も上記した通りである。また、各単量体の使用量は、上記した組成範囲となるように適宜選択すればよい。 Examples of the monomer component used when preparing the monomer emulsion include the above-mentioned monomers, and suitable monomers are also as described above. Further, the amount of each monomer used may be appropriately selected so as to be within the above-mentioned composition range.
　乳化剤としては、特に限定されず、たとえば、ノニオン性乳化剤、アニオン性乳化剤、カチオン性乳化剤などを挙げることができる。 The emulsifier is not particularly limited, and examples thereof include nonionic emulsifiers, anionic emulsifiers, and cationic emulsifiers.
　ノニオン性乳化剤としては、特に限定されず、たとえば、ポリオキシエチレンステアリン酸エステル、ポリオキシエチレンソルビタンアルキルエステルなどのポリオキシアルキレン脂肪酸エステル；ポリオキシエチレンドデシルエーテルなどのポリオキシアルキレンアルキルエーテル；ポリオキシエチレンノニルフェニルエーテルなどのポリオキシアルキレンアルキルフェニルエーテル；などを挙げることができる。これらの中でも、ポリオキシアルキレンアルキルエーテル、ポリオキシアルキレンアルキルフェニルエーテルが好ましく、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルフェニルエーテルがより好ましい。ノニオン性乳化剤の重量平均分子量（ゲルパーミエーションクロマトグラフィ（ＧＰＣ）測定によるポリスチレン換算での重量平均分子量）は、特に限定されないが、通常３００～５０，０００、好ましくは５００～３０，０００、より好ましくは１，０００～１５，０００の範囲である。これらのノニオン性乳化剤は、それぞれ単独で、あるいは２種以上を組み合わせて用いることができる。 The nonionic emulsifier is not particularly limited, and is, for example, a polyoxyalkylene fatty acid ester such as a polyoxyethylene stearate ester or a polyoxyethylene sorbitan alkyl ester; a polyoxyalkylene alkyl ether such as a polyoxyethylene dodecyl ether; a polyoxyethylene. Polyoxyalkylene alkyl phenyl ethers such as nonyl phenyl ethers; and the like. Among these, polyoxyalkylene alkyl ether and polyoxyalkylene alkyl phenyl ether are preferable, and polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether are more preferable. The weight average molecular weight of the nonionic emulsifier (weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC)) is not particularly limited, but is usually 300 to 50,000, preferably 500 to 30,000, more preferably. It is in the range of 1,000 to 15,000. These nonionic emulsifiers can be used alone or in combination of two or more.
　アニオン性乳化剤としては、特に限定されないが、たとえば、ミリスチン酸、パルミチン酸、オレイン酸、リノレン酸などの脂肪酸の塩；ドデシルベンゼンスルホン酸ナトリウムなどのアルキルベンゼンスルホン酸塩；ラウリル硫酸ナトリウムなどの高級アルコール硫酸エステル塩、アルキルリン酸エステルナトリウムなどのリン酸エステル塩、好ましくは疎水基の炭素数が６以上のアルコールのリン酸エステルナトリウムなどの高級アルコール燐酸エステル塩；アルキルスルホコハク酸塩などを挙げることができる。これらのアニオン性乳化剤の中でも、リン酸エステル塩、高級アルコール硫酸エステル塩が好ましく、高級アルコール燐酸エステル塩、高級アルコール硫酸エステル塩がより好ましく、高級アルコール燐酸エステル塩がさらに好ましい。これらのアニオン性乳化剤は、それぞれ単独で、あるいは２種以上を組み合わせて用いることができる。 The anionic emulsifier is not particularly limited, and is, for example, a salt of a fatty acid such as myristic acid, palmitic acid, oleic acid, or linolenic acid; an alkylbenzene sulfonate such as sodium dodecylbenzenesulfonate; a higher alcohol sulfate such as sodium laurylsulfate. Phosphoric acid ester salts such as ester salts and sodium alkyl phosphates, preferably higher alcohol phosphoric acid ester salts such as sodium phosphates of alcohols having a hydrophobic group having 6 or more carbon atoms; alkyl sulfosuccinates and the like can be mentioned. .. Among these anionic emulsifiers, phosphoric acid ester salts and higher alcohol sulfate ester salts are preferable, higher alcohol phosphoric acid ester salts and higher alcohol sulfate ester salts are more preferable, and higher alcohol phosphoric acid ester salts are even more preferable. These anionic emulsifiers can be used alone or in combination of two or more.
　カチオン性乳化剤としては、たとえば、アルキルトリメチルアンモニウムクロライド、ジアルキルアンモニウムクロライド、ベンジルアンモニウムクロライドなどを挙げることができる。 Examples of the cationic emulsifier include alkyltrimethylammonium chloride, dialkylammonium chloride, benzylammonium chloride and the like.
　これら乳化剤は、それぞれ単独で、あるいは２種以上を組み合わせて用いることができるが、中でも、ノニオン性乳化剤、アニオン性乳化剤が好ましく、ノニオン性乳化剤とアニオン性乳化剤とを組み合わせて用いることがより好ましい。ノニオン性乳化剤とアニオン性乳化剤とを組み合わせて用いることにより、乳化重合時における重合装置（たとえば、重合槽）へのポリマーなどの付着による汚れの発生を有効に抑制しつつ、後述する凝固工程において用いる凝固剤の使用量を低減することが可能となり、結果として、最終的に得られるカルボキシル基含有アクリルゴム中における凝固剤量を低減することができ、これにより得られるゴム架橋物の耐水性を向上させることができる。また、ノニオン性乳化剤とアニオン性乳化剤とを組み合わせて用いることにより、乳化作用を高めることができるため、乳化剤自体の使用量をも低減することができ、結果として、最終的に得られるカルボキシル基含有アクリルゴム中に含まれる乳化剤の残留量を低減することができ、これにより、得られるカルボキシル基含有アクリルゴムの耐水性をより高めることができる。 These emulsifiers can be used alone or in combination of two or more, but among them, nonionic emulsifiers and anionic emulsifiers are preferable, and nonionic emulsifiers and anionic emulsifiers are more preferable. By using a combination of a nonionic emulsifier and an anionic emulsifier, it is used in the coagulation step described later while effectively suppressing the generation of stains due to the 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 carboxyl group-containing acrylic rubber can be reduced, thereby improving the water resistance of the obtained rubber crosslinked product. Can be made to. 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, the final obtained contains a carboxyl group. The residual amount of the emulsifier contained in the acrylic rubber can be reduced, whereby the water resistance of the obtained carboxyl group-containing acrylic rubber can be further enhanced.
　乳化剤の使用量は、重合に用いる単量体成分１００重量部に対する、用いる乳化剤の総量で、通常０．０１～１０重量部、好ましくは０．１～５重量部、より好ましくは１～３重量部の範囲である。また、ノニオン性乳化剤とアニオン性乳化剤とを組み合わせて用いる場合の使用割合は、ノニオン性乳化剤／アニオン性乳化剤の重量比で、通常１／９９～９９／１、好ましくは１０／９０～８０／２０、より好ましくは１３／８７～４０／６０、さらに好ましくは１５／８５～３５／６５の範囲である。 The amount of the emulsifier used is the total amount of the emulsifier used with respect to 100 parts by weight of the monomer component used for the polymerization, 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. It is the range of the part. When the nonionic emulsifier and the anionic emulsifier are used in combination, the ratio of use is usually 1/99 to 99/1, preferably 10/90 to 80/20, in terms of the weight ratio of the nonionic emulsifier / anionic emulsifier. , More preferably 13/87 to 40/60, and even more preferably 15/85 to 35/65.
　単量体乳化液調製工程において、（メタ）アクリル酸エステル単量体およびカルボキシル基含有単量体を含む、重合に用いる単量体成分を、水と乳化剤とを用いて乳化させる方法としては、特に限定されないが、単量体成分と、水と、乳化剤とを混合する方法が好ましく、単量体成分と、水と、乳化剤とをホモジナイザーやディスクタービンなどの攪拌機などを用いて攪拌する方法がより好ましい。なお、単量体乳化液には、必要に応じて、粒径調整剤、キレート化剤、酸素捕捉剤などの重合副資材を含有させてもよい。 In the monomer emulsion preparation step, as a method of emulsifying a monomer component used for polymerization, including a (meth) acrylic acid ester monomer and a carboxyl group-containing monomer, using water and an emulsifier, Although not particularly limited, a method of mixing the monomer component, water, and an emulsifier is preferable, and a method of stirring the monomer component, water, and the emulsifier using a stirrer such as a homogenizer or a disk turbine is preferable. More preferred. If necessary, the monomeric emulsion may contain a polymerization auxiliary material such as a particle size adjusting agent, a chelating agent, and an oxygen scavenger.
　単量体乳化液調製工程における水の使用量は、重合に用いる単量体成分１００重量部に対して、好ましくは５～５００重量部、より好ましくは１０～３００重量部、さらに好ましくは２０～２００重量部である。 The amount of water used in the monomer emulsion preparation step is preferably 5 to 500 parts by weight, more preferably 10 to 300 parts by weight, still more preferably 20 to 20 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. It is 200 parts by weight.
　なお、本発明の製造方法においては、重合に用いる単量体成分の全量について、単量体乳化液の状態とし、後述する初期重合工程、単量体乳化液滴下工程、および後反応工程を経ることで、カルボキシル基含有アクリルゴムを得るような態様としてもよいが、重合に用いる単量体成分の全量１００重量％のうち、好ましくは８０～１００重量％、より好ましくは９０～１００重量％について、単量体乳化液の状態とし、残部については、単量体乳化液の状態とせずに、後述する初期重合工程や、後反応工程において、別途添加するような態様としてもよい。 In the production method of the present invention, the total amount of the monomer components used for the polymerization is set to the state of the monomer emulsion, and the initial polymerization step, the monomer emulsifying droplet lowering step, and the post-reaction step described later are performed. This may be an embodiment such as obtaining a carboxyl group-containing acrylic rubber, but preferably 80 to 100% by weight, more preferably 90 to 100% by weight, out of 100% by weight of the total amount of the monomer components used for the polymerization. The residue may be added separately in the initial polymerization step or the post-reaction step, which will be described later, without the state of the monomeric emulsion.
（初期重合工程）
　初期重合工程は、上記単量体乳化液調製工程で調製した単量体乳化液の全量のうち一部に対し、重合開始剤を添加することで、重合反応を開始させる工程である。 (Initial polymerization step)
The initial polymerization step is a step of initiating the polymerization reaction by adding a polymerization initiator to a part of the total amount of the monomeric emulsion prepared in the above-mentioned monomeric emulsion preparation step.
　初期重合工程においては、上記単量体乳化液調製工程で調製した単量体乳化液の全量のうち一部を使用して、重合反応を開始させるものであり、これにより、主としてシード形成を行うものである。初期重合工程においては、重合安定性の観点より、単量体乳化液の全量１００重量％のうち、１．０～２５．０重量％を用いることが好ましく、１．５～２０．０重量％を用いることがより好ましく、２．０～１５．０重量％を用いることがさらに好ましい。 In the initial polymerization step, a part of the total amount of the monomer emulsion prepared in the above-mentioned monomer emulsion preparation step is used to initiate the polymerization reaction, thereby mainly performing seed formation. It is a thing. In the initial polymerization step, from the viewpoint of polymerization stability, it is preferable to use 1.0 to 25.0% by weight, preferably 1.5 to 20.0% by weight, out of 100% by weight of the total amount of the monomeric emulsion. It is more preferable to use 2.0 to 15.0% by weight, and it is further preferable to use 2.0 to 15.0% by weight.
　重合開始剤としては、特に限定されず、乳化重合で通常使用されるものを制限なく用いることができる。重合開始剤としては、たとえば、過酸化物、アゾ化合物、過酸化物と還元剤とからなるレドックス系重合開始剤を用いることが好ましい。 The polymerization initiator is not particularly limited, and those usually used in emulsion polymerization can be used without limitation. As the polymerization initiator, for example, it is preferable to use a peroxide, an azo compound, or a redox-based polymerization initiator composed of a peroxide and a reducing agent.
　過酸化物としては、無機系過酸化物、有機系過酸化物のいずれを用いてもよい。 As the peroxide, either an inorganic peroxide or an organic peroxide may be used.
　無機系過酸化物としては、たとえば、過硫酸ナトリウム、過硫酸カリウム、過酸化水素、過硫酸アンモニウムなどが挙げられる。これらの中でも、過硫酸カリウム、過酸化水素、過硫酸アンモニウムが好ましく、過硫酸カリウムが特に好ましい。 Examples of the inorganic peroxide include sodium persulfate, potassium persulfate, hydrogen peroxide, ammonium persulfate and the like. Among these, potassium persulfate, hydrogen peroxide, and ammonium persulfate are preferable, and potassium persulfate is particularly preferable.
　有機系過酸化物としては、たとえば、２，２－ジ（４，４－ジ－（ｔ－ブチルパーオキシ）シクロヘキシル）プロパン、１－ジ－（ｔ－ヘキシルパーオキシ）シクロヘキサン、１，１－ジ－（ｔ－ブチルパーオキシ）シクロヘキサン、４，４－ジ－（ｔ－ブチルパーオキシ）吉草酸ｎ－ブチル、２，２－ジ－（ｔ－ブチルパーオキシ）ブタン、ｔ－ブチルハイドロパーオキサイド、クメンハイドロパーオキサイド、ジイソプロピルベンゼンハイドロパーオキサイド、パラメンタンハイドロパーオキサイド、ベンゾイルパーオキサイド、１，１，３，３－テトラエチルブチルハイドロパーオキサイド、ｔ－ブチルクミルパーオキサイド、ジ－ｔ－ブチルパーオキサイド、ジ－ｔ－ヘキシルパーオキサイド、ジ（２－ｔ－ブチルパーオキシイソプロピル）ベンゼン、ジクミルパーオキサイド、ジイソブチリルパーオキサイド、ジ（３，５，５－トリメチルヘキサノイル）パーオキサイド、ジラウロイルパーオキサイド、ジコハク酸パーオキサイド、ジベンゾイルパーオキサイド、ジ（３－メチルベンゾイル）パーオキサイド、ベンゾイル（３－メチルベンゾイル）パーオキサイド、ジイソブチリルパーオキシジカーボネート、ジ－ｎ－プロピルパーオキシジカーボネート、ジ（２－エチルヘキシル）パーオキシジカーボネート、ジ－ｓｅｃ－ブチルパーオキシジカーボネート、１，１，３，３－テトラメチルブチルパーオキシネオデカネート、ｔ－ヘキシルパーオキシピバレート、ｔ－ブチルパーオキシネオデカネート、ｔ－ヘキシルパーオキシピバレート、ｔ－ブチルパーオキシピバレート、２，５－ジメチル－２，５－ジ（２－エチルヘキサノイルパーオキシ）ヘキサン、１，１，３，３－テトラメチルブチルパーオキシ－２－エチルヘキサネート、ｔ－ヘキシルパーオキシ－２－エチルヘキサネート、ｔ－ブチルパーオキシ－３，５，５－トリメチルヘキサネート、ｔ－ヘキシルパーオキシイソプロピルモノカーボネート、ｔ－ブチルパーオキシイソプロピルモノカーボネート、ｔ－ブチルパーオキシ－２－エチルヘキシルモノカーボネート、２，５－ジメチル－２，５－ジ（ベンゾイルパーオキシ）ヘキサン、ｔ－ブチルパーオキシアセテート、ｔ－ヘキシルパーオキシベンゾエート、ｔ－ブチルパーオキシベンゾエート、２，５－ジメチル－２，５－ジ（ｔ－ブチルパーオキシ）ヘキサンなどが挙げられる。これらの中でも、ジイソプロピルベンゼンハイドロパーオキサイド、クメンハイドロパーオキサイド、パラメンタンハイドロパーオキサイド、ベンゾイルパーオキサイドが好ましい。 Examples of the organic peroxide include 2,2-di (4,4-di- (t-butylperoxy) cyclohexyl) propane, 1-di- (t-hexylperoxy) cyclohexane, and 1,1-. Di- (t-butylperoxy) cyclohexane, 4,4-di- (t-butylperoxy) n-butyl valerate, 2,2-di- (t-butylperoxy) butane, t-butylhydroper Oxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramentan hydroperoxide, benzoyl peroxide, 1,1,3,3-tetraethylbutylhydroperoxide, t-butylcumyl peroxide, di-t-butylper Oxide, di-t-hexyl peroxide, di (2-t-butyl peroxyisopropyl) benzene, dicumyl peroxide, diisobutyryl peroxide, di (3,5,5-trimethylhexanoyl) peroxide, dilauroyl Peroxide, disuccinic acid peroxide, dibenzoyl peroxide, di (3-methylbenzoyl) peroxide, benzoyl (3-methylbenzoyl) peroxide, diisobutyryl peroxydicarbonate, di-n-propylperoxydicarbonate, Di (2-ethylhexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, 1,1,3,3-tetramethylbutylperoxyneodecanate, t-hexylperoxypivalate, t-butylper Oxyneodecaneate, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, 1,1,3,3 -Tetramethylbutylperoxy-2-ethylhexanate, t-hexylperoxy-2-ethylhexanate, t-butylperoxy-3,5,5-trimethylhexanate, t-hexylperoxyisopropylmonocarbonate, t-Butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate, t-hexylper Examples thereof include oxybenzoate, t-butylperoxybenzoate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and the like. Among these, diisopropylbenzene hydroperoxide, cumene hydroperoxide, paramentan hydroperoxide, and benzoyl peroxide are preferable.
　アゾ化合物としては、たとえば、アゾビスイソブチロニトリル、４，４’－アゾビス（４－シアノ吉草酸）、２，２’－アゾビス［２－（２－イミダゾリン－２－イル）プロパン、２，２’－アゾビス（プロパン－２－カルボアミジン）、２，２’－アゾビス［Ｎ－（２－カルボキシエチル）－２－メチルプロパンアミド］、２，２’－アゾビス｛２－［１－（２－ヒドロキシエチル）－２－イミダゾリン－２－イル］プロパン｝、２，２’－アゾビス（１－イミノ－１－ピロリジノ－２－メチルプロパン）、２，２’－アゾビス｛２－メチル－Ｎ－［１，１－ビス（ヒドロキシメチル）－２－ヒドロキシエチル］プロパンアミド｝などが挙げられる。 Examples of the azo compound include azobisisobutyronitrile, 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis [2- (2-imidazolin-2-yl) propane, 2, 2'-azobis (propane-2-carboamidine), 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropaneamide], 2,2'-azobis {2- [1- (2) -Hydroxyethyl) -2-imidazolin-2-yl] propane}, 2,2'-azobis (1-imino-1-pyrrolidino-2-methylpropane), 2,2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propanamide} and the like can be mentioned.
　これらの過酸化物およびアゾ化合物は、１種単独で、または２種以上を併せて使用することができる。初期重合工程における過酸化物およびアゾ化合物の使用量は、重合に用いる単量体成分１００重量部に対して、好ましくは０．００１～０．０２０重量部、より好ましくは０．００２～０．０１５重量部、さらに好ましくは０．００３～０．０１０重量部である。 These peroxides and azo compounds can be used alone or in combination of two or more. The amount of the peroxide and the azo compound used in the initial polymerization step is preferably 0.001 to 0.020 parts by weight, more preferably 0.002 to 0 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. It is 015 parts by weight, more preferably 0.003 to 0.010 parts by weight.
　過酸化物と組み合わせて用いられる還元剤としては、乳化重合のレドックス触媒として使用されるものであれば制限なく用いることができる。還元剤としては、少なくとも２種の還元剤を用いることが好ましく、中でも、還元状態にある金属イオン化合物と、それ以外の還元剤との組み合わせが好適である。 The reducing agent used in combination with the peroxide can be used without limitation as long as it is used as a redox catalyst for emulsion polymerization. As the reducing agent, it is preferable to use at least two kinds of reducing agents, and among them, a combination of a metal ion compound in a reduced state and another reducing agent is preferable.
　還元状態にある金属イオン化合物としては、特に限定されないが、たとえば、硫酸第一鉄、ヘキサメチレンジアミン四酢酸鉄ナトリウム、ナフテン酸第一銅などが挙げられる。これらの中でも、硫酸第一鉄が好ましい。 The metal ion compound in the reduced state is not particularly limited, and examples thereof include ferrous sulfate, sodium hexamethylenediamine tetraacetate, and ferrous naphthenate. Among these, ferrous sulfate is preferable.
　還元状態にある金属イオン化合物は、１種単独で、または２種以上を併せて使用することができる。初期重合工程における還元状態にある金属イオン化合物の使用量は、重合に用いる単量体成分１００重量部に対して、好ましくは０．０００５～０．００３０重量部、より好ましくは０．０００７～０．００２５重量部、さらに好ましくは０．００１０～０．００２０重量部である。 The metal ion compound in the reduced state can be used alone or in combination of two or more. The amount of the metal ion compound in the reduced state in the initial polymerization step is preferably 0.0005 to 0.0030 parts by weight, more preferably 0.0007 to 0, based on 100 parts by weight of the monomer component used for the polymerization. It is 0025 parts by weight, more preferably 0.0010 to 0.0020 parts by weight.
　還元状態にある金属イオン化合物以外の還元剤としては、特に限定されないが、たとえば、アスコルビン酸、アスコルビン酸ナトリウム、アスコルビン酸カリウムなどのアスコルビン酸またはその塩；エリソルビン酸、エリソルビン酸ナトリウム、エリソルビン酸カリウムなどのエリソルビン酸またはその塩；ホルムアルデヒドスルホキシル酸ナトリウムなどのスルフィン酸塩；亜硫酸ナトリウム、亜硫酸カリウム、亜硫酸水素ナトリウム、アルデヒド亜硫酸水素ナトリウム、亜硫酸水素カリウムの亜硫酸塩；ピロ亜硫酸ナトリウム、ピロ亜硫酸カリウム、ピロ亜硫酸水素ナトリウム、ピロ亜硫酸水素カリウムなどのピロ亜硫酸塩；チオ硫酸ナトリウム、チオ硫酸カリウムなどのチオ硫酸塩；亜燐酸、亜燐酸ナトリウム、亜燐酸カリウム、亜燐酸水素ナトリウム、亜燐酸水素カリウムの亜燐酸またはその塩；ピロ亜燐酸、ピロ亜燐酸ナトリウム、ピロ亜燐酸カリウム、ピロ亜燐酸水素ナトリウム、ピロ亜燐酸水素カリウムなどのピロ亜燐酸またはその塩；などが挙げられる。これらの中でも、アスコルビン酸またはその塩、ホルムアルデヒドスルホキシル酸ナトリウムが好ましい。 The reducing agent other than the metal ion compound in the reduced state is not particularly limited, and is, for example, ascorbic acid such as ascorbic acid, sodium ascorbate, potassium ascorbate or a salt thereof; Elysorbic acid or a salt thereof; sulphinates such as sodium formaldehyde sulfoxylate; sodium bisulfite, potassium sulfite, sodium bisulfite, sodium aldehyde bisulfite, sodium bisulfite sulfite; sodium pyrosulfite, potassium pyrosulfite, pyrosulfite Pyro sulfites such as sodium bisulfite and potassium hydrogen sulfite; thiosulfates such as sodium thiosulfite and potassium thiosulfite; phosphite, sodium bisulfite, potassium bisulfite, sodium bisulfite, potassium hydrogen phosphite Examples thereof include pyrophosphoric acid such as pyrophosphoric acid, sodium pyrophosphite, potassium pyrosulfite, sodium hydrogen pyrosulfite, and potassium hydrogen pyrosulfite, or salts thereof. Among these, ascorbic acid or a salt thereof and sodium formaldehyde sulfoxylate are preferable.
　還元状態にある金属イオン化合物以外の還元剤は、１種単独で、または２種以上を併せて使用することができる。初期重合工程における還元状態にある金属イオン化合物以外の還元剤の使用量は、重合に用いる単量体成分１００重量部に対して、好ましくは０．００５～０．０８０重量部、より好ましくは０．０１０～０．０６０重量部、さらに好ましくは０．０２０～０．０４０重量部である。 The reducing agent other than the metal ion compound in the reduced state can be used alone or in combination of two or more. The amount of the reducing agent other than the metal ion compound in the reduced state in the initial polymerization step is preferably 0.005 to 0.080 parts by weight, more preferably 0, with respect to 100 parts by weight of the monomer component used for the polymerization. It is 010 to 0.060 parts by weight, more preferably 0.020 to 0.040 parts by weight.
　還元状態にある金属イオン化合物と、還元状態にある金属イオン化合物以外の還元剤との好ましい組み合わせとしては、硫酸第一鉄と、アスコルビン酸もしくはその塩および／またはホルムアルデヒドスルホキシル酸ナトリウムとの組み合わせが挙げられ、硫酸第一鉄と、アスコルビン酸塩および／またはホルムアルデヒドスルホキシル酸ナトリウムとの組み合わせがより好ましく、硫酸第一鉄と、ホルムアルデヒドスルホキシル酸ナトリウムとの組み合わせが特に好ましい。 A preferable combination of the metal ion compound in the reduced state and the reducing agent other than the metal ion compound in the reduced state is a combination of ferrous sulfate and ascorbic acid or a salt thereof and / or sodium formaldehyde sulfoxylate. The combination of ferrous sulfate and ascorbic acid salt and / or sodium formaldehyde sulfoxylate is more preferable, and the combination of ferrous sulfate and sodium formaldehyde sulfoxylate is particularly preferable.
　初期重合工程における水の使用量は、重合に用いる単量体成分１００重量部に対して、好ましくは５～５００重量部、より好ましくは１０～３００重量部、さらに好ましくは２０～２００重量部である。 The amount of water used in the initial polymerization step is preferably 5 to 500 parts by weight, more preferably 10 to 300 parts by weight, still more preferably 20 to 200 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. be.
　初期重合工程における、重合温度や重合時間は、特に限定されないが、重合温度は、好ましくは０～１００℃、より好ましくは５～８０℃、さらに好ましくは１０～５０℃である。また、重合時間は、好ましくは０．３～２．０時間、より好ましくは０．５～１．０時間である。 The polymerization temperature and the polymerization time in the initial polymerization step are not particularly limited, but the polymerization temperature is preferably 0 to 100 ° C, more preferably 5 to 80 ° C, and even more preferably 10 to 50 ° C. The polymerization time is preferably 0.3 to 2.0 hours, more preferably 0.5 to 1.0 hours.
　なお、初期重合工程において、重合に用いる単量体成分のうち一部について、単量体乳化液の状態ではなく、そのまま重合反応系に添加し、初期重合工程における重合反応を開始させるような態様としてもよい。 In the initial polymerization step, a part of the monomer components used for the polymerization is added to the polymerization reaction system as it is, not in the state of the monomer emulsion, to start the polymerization reaction in the initial polymerization step. May be.
（単量体乳化液滴下工程）
　単量体乳化液滴下工程は、初期重合工程を経た重合反応系に対し、単量体乳化液調製工程で調製した単量体乳化液のうち残部を、重合反応系に連続的あるいは継続的に滴下することで、重合反応を進行させる工程である。 (Monomer emulsification droplet lower process)
In the monomer emulsification droplet lowering step, the remainder of the monomer emulsifying liquid prepared in the monomer emulsifying liquid preparation step is continuously or continuously to the polymerization reaction system with respect to the polymerization reaction system that has undergone the initial polymerization step. It is a step of advancing the polymerization reaction by dropping.
　単量体乳化液滴下工程においては、単量体乳化液調製工程で調製した単量体乳化液のうち残部を、重合反応系に連続的または継続的、好ましくは連続的に滴下することで、重合反応を進行させるものであり、この際に滴下時間としては、特に限定されないが、得られるカルボキシル基含有アクリルゴムの、エタノール水溶液抽出操作により抽出を行った際における、後述する後反応工程開始時の重合転化率を制御するという観点より、好ましくは２．０～２０時間であり、より好ましくは３．０～１０．０時間である。なお、単量体乳化液滴下工程においては、単量体乳化液の滴下終了後、後述する後反応工程において後反応を開始するための重合転化率に到達するまで、重合反応を継続してもよい。 In the monomer emulsification droplet lowering step, the remainder of the monomer emulsifying solution prepared in the monomer emulsifying solution preparation step is continuously or continuously, preferably continuously dropped onto the polymerization reaction system. The polymerization reaction is allowed to proceed, and the dropping time is not particularly limited at this time, but when the obtained carboxyl group-containing acrylic rubber is extracted by the ethanol aqueous solution extraction operation, at the start of the post-reaction step described later. From the viewpoint of controlling the polymerization conversion rate of the above, it is preferably 2.0 to 20 hours, more preferably 3.0 to 10.0 hours. In the step below the monomer emulsified droplet, even if the polymerization reaction is continued until the polymerization conversion rate for starting the post-reaction is reached in the post-reaction step described later after the dropping of the monomer emulsified solution is completed. good.
　また、単量体乳化液滴下工程においては、単量体乳化液調製工程で調製した単量体乳化液のうち残部を、重合反応系に連続的あるいは継続的に滴下することで重合反応を進行させるような態様であればよいが、単量体乳化液に加えて、重合開始剤についても、重合反応系に連続的あるいは継続的に滴下するような態様とすることが好ましく、連続的に滴下するような態様とすることがより好ましい。この際において、重合開始剤としては、過酸化物、アゾ化合物、過酸化物と還元剤とからなるレドックス系重合開始剤を用いることが好ましい。 Further, in the monomer emulsion lowering step, the polymerization reaction proceeds by continuously or continuously dropping the remainder of the monomeric emulsion prepared in the monomer emulsion preparation step onto the polymerization reaction system. However, in addition to the monomeric emulsion, it is preferable that the polymerization initiator is continuously or continuously added dropwise to the polymerization reaction system, and the polymerization initiator is continuously added dropwise. It is more preferable to have such an embodiment. At this time, as the polymerization initiator, it is preferable to use a peroxide, an azo compound, and a redox-based polymerization initiator composed of a peroxide and a reducing agent.
　単量体乳化液滴下工程において、単量体乳化液のうち残部とともに、重合開始剤を重合反応系に連続的あるいは継続的に滴下する際には、これらは別々の滴下装置を用いて重合反応系に滴下してもよいし、また、過酸化物と還元剤とからなるレドックス系重合開始剤を用いる場合には、少なくとも、過酸化物と還元剤とについては、予め混合し、必要に応じて水溶液の状態として同じ滴下装置から重合反応系に滴下してもよい。 In the step below the monomer emulsifying droplets, when the polymerization initiator is continuously or continuously added dropwise to the polymerization reaction system together with the rest of the monomeric emulsion, these are polymerized using separate dropping devices. It may be added dropwise to the system, or when a redox-based polymerization initiator composed of a peroxide and a reducing agent is used, at least the peroxide and the reducing agent are mixed in advance and, if necessary. It may be dropped onto the polymerization reaction system from the same dropping device as an aqueous solution.
　単量体乳化液滴下工程における過酸化物およびアゾ化合物の使用量は、重合に用いる単量体成分１００重量部に対して、好ましくは０．００３～０．０２０重量部、より好ましくは０．００５～０．０１５重量部、さらに好ましくは０．００６～０．０１２重量部である。また、単量体乳化液滴下工程における還元剤の使用量は、重合に用いる単量体成分１００重量部に対して、好ましくは０．０５～０．５０重量部、より好ましくは０．１０～０．４０重量部、さらに好ましくは０．１５～０．３５重量部である。 The amount of the peroxide and the azo compound used in the step below the monomer emulsified droplet is preferably 0.003 to 0.020 part by weight, more preferably 0, with respect to 100 parts by weight of the monomer component used for the polymerization. It is 005 to 0.015 parts by weight, more preferably 0.006 to 0.012 parts by weight. The amount of the reducing agent used in the step below the monomer emulsifying droplet is preferably 0.05 to 0.50 parts by weight, more preferably 0.10 to 0 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. It is 0.40 parts by weight, more preferably 0.15 to 0.35 parts by weight.
　単量体乳化液滴下工程における、重合温度は、特に限定されないが、重合温度は、好ましくは０～１００℃、より好ましくは５～８０℃、さらに好ましくは１０～５０℃である。 The polymerization temperature in the step below the monomer emulsification droplet is not particularly limited, but the polymerization temperature is preferably 0 to 100 ° C, more preferably 5 to 80 ° C, and even more preferably 10 to 50 ° C.
（後反応工程）
　後反応工程は、上記した単量体乳化液滴下工程における単量体乳化液の滴下を終了した後、重合反応系に、重合開始剤および／または分子量調整剤を添加して、重合反応を継続する工程である。 (Post-reaction process)
In the post-reaction step, after the dropping of the monomer emulsifying solution in the above-mentioned step below the monomer emulsifying droplet is completed, a polymerization initiator and / or a molecular weight adjusting agent is added to the polymerization reaction system to continue the polymerization reaction. It is a process to be polymerized.
　後反応工程においては、上述した単量体乳化液滴下工程における単量体乳化液の滴下が終了した後に、重合開始剤および／または分子量調整剤を添加して、重合反応を継続するものであればよいが、得られるカルボキシル基含有アクリルゴムのエタノール水溶液抽出量を上記した範囲とするという観点より、上述した単量体乳化液滴下工程における単量体乳化液の滴下が終了した後、重合転化率が、好ましくは８０～９４％となった時点、より好ましくは８１～９３％となった時点、さらに好ましくは８３～９２％、さらにより好ましくは８５～９１％となった時点で、重合開始剤および／または分子量調整剤を添加して、重合反応を継続するものであることが好ましい。なお、単量体乳化液滴下工程における単量体乳化液の滴下終了時の重合転化率は、たとえば、初期重合工程における重合開始剤（たとえば、過酸化物、アゾ化合物や過酸化物と組み合わせて用いられる還元剤）の使用量を調整する方法や、単量体乳化液滴下工程における重合開始剤（たとえば、過酸化物、アゾ化合物や過酸化物と組み合わせて用いられる還元剤）の使用量を調整する方法、単量体乳化液滴下工程における滴下時間を調整する方法などにより調整することができる。そして、後反応工程においては、単量体乳化液滴下工程における単量体乳化液の滴下終了後、重合転化率が上記範囲となった時点で、重合開始剤および／または分子量調整剤を添加して、重合反応を継続することが好ましい。 In the post-reaction step, the polymerization reaction may be continued by adding a polymerization initiator and / or a molecular weight adjusting agent after the dropping of the monomer emulsifying solution in the above-mentioned monomer emulsifying droplet lower step is completed. However, from the viewpoint that the amount of the obtained carboxyl group-containing acrylic rubber extracted from the ethanol aqueous solution is within the above range, the polymerization conversion is completed after the dropping of the monomer emulsifying solution in the above-mentioned step below the monomer emulsifying droplet is completed. Polymerization starts when the ratio is preferably 80 to 94%, more preferably 81 to 93%, still more preferably 83 to 92%, and even more preferably 85 to 91%. It is preferable to add an agent and / or a molecular weight adjusting agent to continue the polymerization reaction. The polymerization conversion rate at the end of dropping the monomer emulsion in the step below the monomer emulsifying droplet is, for example, in combination with a polymerization initiator (for example, a peroxide, an azo compound or a peroxide) in the initial polymerization step. A method for adjusting the amount of the reducing agent used) and the amount of the polymerization initiator (for example, a peroxide, an azo compound or a reducing agent used in combination with the peroxide) in the lower step of the monomer emulsified droplet. It can be adjusted by a method of adjusting, a method of adjusting the dropping time in the step of lowering the monomer emulsified droplet, or the like. Then, in the post-reaction step, a polymerization initiator and / or a molecular weight adjusting agent is added when the polymerization conversion rate reaches the above range after the dropping of the monomer emulsifying solution in the step below the monomer emulsifying droplet is completed. Therefore, it is preferable to continue the polymerization reaction.
　後反応工程によれば、上記した単量体乳化液滴下工程における単量体乳化液の滴下を終了した後、重合開始剤および／または分子量調整剤を添加して、重合反応を継続することにより、重合開始剤および／または分子量調整剤の作用により、比較的低分子量である重合体成分の生成を促進させることができ、これにより、得られるカルボキシル基含有アクリルゴムのエタノール水溶液抽出量を制御できるものである。そのため、後反応工程においては、重合転化率が上記範囲となった段階で、重合開始剤および／または分子量調整剤を添加して、重合反応を継続することが好適である。 According to the post-reaction step, after the dropping of the monomer emulsifying solution in the above-mentioned step below the monomer emulsifying droplet is completed, a polymerization initiator and / or a molecular weight adjusting agent is added to continue the polymerization reaction. By the action of the polymerization initiator and / or the molecular weight modifier, the formation of a polymer component having a relatively low molecular weight can be promoted, whereby the amount of the obtained carboxyl group-containing acrylic rubber extracted from the ethanol aqueous solution can be controlled. It is a thing. Therefore, in the post-reaction step, it is preferable to add a polymerization initiator and / or a molecular weight adjuster when the polymerization conversion rate is within the above range to continue the polymerization reaction.
　後反応工程で用いる重合開始剤としては、特に限定されないが、過酸化物、アゾ化合物、過酸化物と還元剤とからなるレドックス系重合開始剤を用いることが好ましい。後反応工程における過酸化物およびアゾ化合物の使用量は、重合に用いる単量体成分１００重量部に対して、好ましくは０．０１５～０．０４５重量部、より好ましくは０．０２０～０．０４０重量部、さらに好ましくは０．０２５～０．０３５重量部である。また、後反応工程における還元剤の使用量は、重合に用いる単量体成分１００重量部に対して、好ましくは０．００４～０．０１５重量部、より好ましくは０．００５～０．０１２重量部、さらに好ましくは０．００６～０．０１０重量部である。 The polymerization initiator used in the post-reaction step is not particularly limited, but it is preferable to use a peroxide, an azo compound, or a redox-based polymerization initiator composed of a peroxide and a reducing agent. The amount of the peroxide and the azo compound used in the post-reaction step is preferably 0.015 to 0.045 parts by weight, more preferably 0.020 to 0, with respect to 100 parts by weight of the monomer component used for the polymerization. It is 040 parts by weight, more preferably 0.025 to 0.035 parts by weight. The amount of the reducing agent used in the post-reaction step is preferably 0.004 to 0.015 parts by weight, more preferably 0.005 to 0.012 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. Parts, more preferably 0.006 to 0.010 parts by weight.
　また、後反応工程で用いる分子量調整剤としては、特に限定されないが、ｎ－ブチルメルカプタン、ｔ－ドデシルメルカプタン等のメルカプタン類；テトラエチルチウラムスルフィド、ジベンタメチレンチウラムヘキサスルフィド等のスルフィド類；α－メチルスチレン２量体；四塩化炭素等が挙げられる。 The molecular weight adjusting agent used in the post-reaction step is not particularly limited, but mercaptans such as n-butyl mercaptan and t-dodecyl mercaptan; sulfides such as tetraethylthium sulfide and diventamethylene thiuram hexasulfide; α-methyl. Sulfide dimer; carbon tetrachloride and the like can be mentioned.
　後反応工程における分子量調整剤の使用量は、重合に用いる単量体成分１００重量部に対して、好ましくは０．００６～０．０２０重量部、より好ましくは０．００７～０．０１５重量部、さらに好ましくは０．００８～０．０１２重量部である。 The amount of the molecular weight adjusting agent used in the post-reaction step is preferably 0.006 to 0.020 parts by weight, more preferably 0.007 to 0.015 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. , More preferably 0.008 to 0.012 parts by weight.
　そして、後反応工程においては、重合反応系に、重合開始剤および／または分子量調整剤を添加し、最終的な重合転化率（後反応工程における重合を停止する際の重合転化率）が、好ましくは９５％以上であり、より好ましくは９７％以上、さらに好ましくは９８％以上となるまで重合反応を継続することが好ましい。最終的な重合転化率の上限は特に限定されないが、９９．５％以下である。 Then, in the post-reaction step, a polymerization initiator and / or a molecular weight adjusting agent is added to the polymerization reaction system, and the final polymerization conversion rate (polymerization conversion rate when the polymerization in the post-reaction step is stopped) is preferable. Is 95% or more, more preferably 97% or more, still more preferably 98% or more, and it is preferable to continue the polymerization reaction. The upper limit of the final polymerization conversion rate is not particularly limited, but is 99.5% or less.
　重合反応を停止する際には、重合停止剤を用いることができる。重合停止剤としては、たとえば、ヒドロキシルアミン、ヒドロキシアミン硫酸塩、ジエチルヒドロキシアミン、ヒドロキシアミンスルホン酸およびそのアルカリ金属塩、ジメチルジチオカルバミン酸ナトリウム、ハイドロキノンなどが挙げられる。重合停止剤の使用量は、特に限定されないが、重合に用いる単量体成分１００重量部に対して、好ましくは０．１～２重量部である。 When stopping the polymerization reaction, a polymerization terminator can be used. 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 component used for the polymerization.
　なお、本発明のカルボキシル基含有アクリルゴムを形成するための単量体のうち、カルボキシル基含有単量体は、他の単量体と比較して重合反応性が比較的低く、他の単量体と比較して残存し易い傾向にある。そのため、後反応工程開始時には、重合反応系中に含まれる全単量体中における、カルボキシル基含有単量体の含有割合が比較的高くなる傾向にあるため、このような傾向を考慮した上で、後反応工程に係る重合を開始する際における条件、たとえば、後反応を開始する際における重合転化率や最終的な重合転化率等を制御することが好ましく、これにより、エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量（すなわち、比較的低分子量である重合体成分に含まれるカルボキシル基の量）を制御することができる。 Among the monomers for forming the carboxyl group-containing acrylic rubber of the present invention, the carboxyl group-containing monomer has a relatively low polymerization reactivity as compared with other monomers, and is another single amount. It tends to remain more easily than the body. Therefore, at the start of the post-reaction step, the content ratio of the carboxyl group-containing monomer in all the monomers contained in the polymerization reaction system tends to be relatively high, and this tendency is taken into consideration. It is preferable to control the conditions for starting the polymerization related to the post-reaction step, for example, the polymerization conversion rate and the final polymerization conversion rate at the time of starting the post-reaction, thereby extracting by the ethanol aqueous solution extraction operation. The amount of change in the carboxyl group content (that is, the amount of the carboxyl group contained in the polymer component having a relatively low molecular weight) can be controlled.
　また、上述したように、後反応工程における重合は、比較的低分子量である重合体成分の生成を促進するものである。そのため、エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量（すなわち、比較的低分子量である重合体成分に含まれるカルボキシル基の量）を調整するという観点より、重合に用いる全単量体中における、カルボキシル基含有単量体の含有割合を調整する方法や、重合に用いるカルボキシル基含有単量体の全量のうち一部を、初期重合工程において添加する方法や、後反応工程において添加する方法などを採用することで、後反応工程に係る重合を開始する際における、重合反応系中に含まれる未反応のカルボキシル基含有単量体の含有比率を調整する方法を採用してもよい。 Further, as described above, the polymerization in the post-reaction step promotes the production of the polymer component having a relatively low molecular weight. Therefore, from the viewpoint of adjusting the amount of change in the carboxyl group content (that is, the amount of the carboxyl group contained in the polymer component having a relatively low molecular weight) when the extraction is performed by the ethanol aqueous solution extraction operation, the polymerization is carried out. A method of adjusting the content ratio of the carboxyl group-containing monomer in all the monomers used, a method of adding a part of the total amount of the carboxyl group-containing monomer used for polymerization in the initial polymerization step, and later. By adopting a method of addition in the reaction step, a method of adjusting the content ratio of the unreacted carboxyl group-containing monomer contained in the polymerization reaction system at the start of the polymerization related to the post-reaction step is adopted. You may.
　なお、たとえば、重合に用いるカルボキシル基含有単量体の全量のうち一部を、初期重合工程において添加する方法によれば、重合初期の段階において、比較的多くのカルボキシル基含有単量体を重合反応系に存在させることができ、これにより、重合反応にける、カルボキシル基含有単量体の消費を促進させることができ、結果として、後反応工程に係る重合を開始する際における、重合反応系中に含まれる全単量体中における、カルボキシル基含有単量体の含有割合を比較的低いものとすることができる。 For example, according to the method of adding a part of the total amount of the carboxyl group-containing monomer used for the polymerization in the initial polymerization step, a relatively large amount of the carboxyl group-containing monomer is polymerized at the initial stage of the polymerization. It can be present in the reaction system, whereby the consumption of the carboxyl group-containing monomer in the polymerization reaction can be promoted, and as a result, the polymerization reaction system at the time of initiating the polymerization related to the post-reaction step. The content ratio of the carboxyl group-containing monomer in all the monomers contained therein can be relatively low.
　後反応工程における、重合温度は、特に限定されないが、重合温度は、好ましくは０～１００℃、より好ましくは５～８０℃、さらに好ましくは１０～５０℃である。 The polymerization temperature in the post-reaction step is not particularly limited, but the polymerization temperature is preferably 0 to 100 ° C, more preferably 5 to 80 ° C, still more preferably 10 to 50 ° C.
（凝固工程）
　そして、本発明の製造方法においては、後反応工程を経て得られた乳化重合液と、凝固剤とを接触させることで、含水クラムを生成させる凝固工程をさらに備えていることが好ましい。 (Coagulation process)
The production method of the present invention preferably further includes a coagulation step of forming a hydrous crumb by contacting the emulsion polymerization solution obtained through the post-reaction step with the coagulant.
　凝固剤としては、特に限定されないが、たとえば、１～３価の金属塩が挙げられる。１～３価の金属塩は、水に溶解させた場合に１～３価の金属イオンとなる金属を含む塩であり、特に限定されないが、たとえば、塩酸、硝酸および硫酸等から選ばれる無機酸や酢酸等の有機酸と、ナトリウム、カリウム、リチウム、マグネシウム、カルシウム、亜鉛、チタン、マンガン、鉄、コバルト、ニッケル、アルミニウムおよびスズ等から選ばれる金属との塩が挙げられる。また、これらの金属の水酸化物なども用いることもできる。 The coagulant is not particularly limited, and examples thereof include monovalent to trivalent metal salts. The monovalent to trivalent metal salt is a salt containing a metal that becomes a 1 to trivalent metal ion when dissolved in water, and is not particularly limited, but is an inorganic acid selected from, for example, hydrochloric acid, nitric acid, sulfuric acid and the like. And salts of organic acids such as acetic acid and metals selected from sodium, potassium, lithium, magnesium, calcium, zinc, titanium, manganese, iron, cobalt, nickel, aluminum, tin and the like. Further, hydroxides of these metals and the like can also be used.
　１～３価の金属塩の具体例としては、塩化ナトリウム、塩化カリウム、塩化リチウム、塩化マグネシウム、塩化カルシウム、塩化亜鉛、塩化チタン、塩化マンガン、塩化鉄、塩化コバルト、塩化ニッケル、塩化アルミニウム、塩化スズなどの金属塩化物；硝酸ナトリウム、硝酸カリウム、硝酸リチウム、硝酸マグネシウム、硝酸カルシウム、硝酸亜鉛、硝酸チタン、硝酸マンガン、硝酸鉄、硝酸コバルト、硝酸ニッケル、硝酸アルミニウム、硝酸スズなどの硝酸塩；硫酸ナトリウム、硫酸カリウム、硫酸リチウム、硫酸マグネシウム、硫酸カルシウム、硫酸亜鉛、硫酸チタン、硫酸マンガン、硫酸鉄、硫酸コバルト、硫酸ニッケル、硫酸アルミニウム、硫酸スズなどの硫酸塩；等が挙げられる。これらのなかでも、塩化カルシウム、塩化ナトリウム、硫酸アルミニウム、塩化マグネシウム、硫酸マグネシウム、塩化亜鉛、硫酸亜鉛、硫酸ナトリウムが好ましい。また、これらは一種単独でまたは複数種併せて用いることができる。 Specific examples of the 1- to trivalent metal salt include sodium chloride, potassium chloride, lithium chloride, magnesium chloride, calcium chloride, zinc chloride, titanium chloride, manganese chloride, iron chloride, cobalt chloride, nickel chloride, aluminum chloride, and chloride. Metal chlorides such as tin; Nitrate such as sodium nitrate, potassium nitrate, lithium nitrate, magnesium nitrate, calcium nitrate, zinc nitrate, titanium nitrate, manganese nitrate, iron nitrate, cobalt nitrate, nickel nitrate, aluminum nitrate, tin nitrate; sodium sulfate , Potassium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, titanium sulfate, manganese sulfate, iron sulfate, cobalt sulfate, nickel sulfate, aluminum sulfate, sulfates such as tin sulfate; and the like. Among these, calcium chloride, sodium chloride, aluminum sulfate, magnesium chloride, magnesium sulfate, zinc chloride, zinc sulfate and sodium sulfate are preferable. In addition, these can be used alone or in combination of two or more.
　凝固剤の使用量は、重合に用いた単量体成分１００重量部に対し、好ましくは０．０１～１００重量部、より好ましくは０．１～５０重量部、さらに好ましくは１～３０重量部である。凝固剤の使用量を上記範囲とすることにより、凝固工程におけるカルボキシル基含有アクリルゴムの凝固を十分なものとしながら、得られるカルボキシル基含有アクリルゴムを耐水性に優れたものとすることができる。 The amount of the coagulant used is preferably 0.01 to 100 parts by weight, more preferably 0.1 to 50 parts by weight, still more preferably 1 to 30 parts by weight, based on 100 parts by weight of the monomer component used for the polymerization. Is. By setting the amount of the coagulant to be used within the above range, the obtained carboxyl group-containing acrylic rubber can be made excellent in water resistance while the coagulation of the carboxyl group-containing acrylic rubber in the coagulation step is sufficient.
　凝固工程における、凝固剤を含有する水溶液の温度（すなわち、凝固温度）は、特に限定されないが、凝固により生成する含水クラムの粒径をより好適に制御するという観点より、好ましくは５０℃以上であり、より好ましくは５０～９５℃、さらに好ましくは６０～９０℃である。 The temperature of the aqueous solution containing the coagulant (that is, the coagulation temperature) in the coagulation step is not particularly limited, but is preferably 50 ° C. or higher from the viewpoint of more preferably controlling the particle size of the hydrous crumb produced by coagulation. Yes, more preferably 50 to 95 ° C, still more preferably 60 to 90 ° C.
（洗浄工程）
　また、本発明の製造方法においては、上記した凝固工程において得られた含水クラムに対して、洗浄を行う洗浄工程をさらに備えていることが好ましい。 (Washing process)
Further, in the production method of the present invention, it is preferable that the water-containing crumb obtained in the above-mentioned solidification step is further provided with a washing step for washing.
　洗浄工程における洗浄方法としては、特に限定されないが、たとえば、上記した凝固工程により得られた含水クラムを、水で水洗する方法が挙げられ、好適には、上記した凝固工程により得られた含水クラムを、水と混合する方法などが挙げられる。水洗時の温度としては、特に限定されないが、好ましくは５～６０℃、より好ましくは１０～５０℃であり、混合時間は１～６０分、より好ましくは２～３０分である。 The cleaning method in the cleaning step is not particularly limited, and examples thereof include a method of washing the water-containing crumb obtained by the above-mentioned coagulation step with water, and preferably, the water-containing crumb obtained by the above-mentioned coagulation step. Is mixed with water. 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.
　また、洗浄工程において、含水クラムと混合する、水の量は、特に限定されないが、水洗効率をより高めるという観点より、重合に用いた単量体成分１００重量部に対して、５０重量部以上となる量とすることが好ましく、より好ましくは５０～１５０００重量部となる量、さらに好ましくは１００～１００００重量部となる量、特に好ましくは５００～５０００重量部となる量である。 Further, in the washing step, the amount of water mixed with the water-containing crumb is not particularly limited, but from the viewpoint of further improving the washing efficiency, 50 parts by weight or more with respect to 100 parts by weight of the monomer component used for the polymerization. The amount is preferably 50 to 15,000 parts by weight, more preferably 100 to 10000 parts by weight, and particularly preferably 500 to 5000 parts by weight.
　水洗時間は、特に限定されないが、好ましくは１～１２０分であり、より好ましくは２～６０分、さらに好ましくは３～３０分である。 The washing time with water is not particularly limited, but is preferably 1 to 120 minutes, more preferably 2 to 60 minutes, and even more preferably 3 to 30 minutes.
　また、洗浄工程における水洗回数は、特に限定されず、好ましくは１～１０回であり、より好ましくは１～５回、さらに好ましくは１～３回である。なお、本発明において、水洗回数とは、含水クラムに対し水を添加し、次いで、所定時間混合を行った後、含水クラムと、水洗に使用した水とを分離する操作を、１回の水洗とした場合における回数である。すなわち、たとえば、水洗回数２回とは、含水クラムに対し水を添加し、次いで、所定時間混合を行った後、含水クラムと、水洗に使用した水とを分離する操作を行い、これに続いて、さらに、含水クラムに対し水を添加し、次いで、所定時間混合を行った後、含水クラムと、水洗に使用した水とを分離する操作を行うことを意味する。なお、水洗回数を２回以上とする場合における、水洗に使用する水の温度、水の量、および水洗時間は、同じとしてもよいし、あるいは、異なるものとしてもよい。 The number of washings with water in the washing step is not particularly limited, and is preferably 1 to 10 times, more preferably 1 to 5 times, and further preferably 1 to 3 times. In the present invention, the number of washings with water means the operation of adding water to the water-containing crumb, mixing the water-containing crumbs for a predetermined time, and then separating the water-containing crumbs from the water used for washing with water once. It is the number of times in the case of. That is, for example, when the number of washings with water is twice, water is added to the water-containing crumb, and then the water-containing crumb is mixed for a predetermined time, and then the water-containing crumb and the water used for washing are separated from each other. Further, it means that water is added to the water-containing crumb, and then the water-containing crumb is mixed for a predetermined time, and then the water-containing crumb and the water used for washing are separated. When the number of washings is two or more, the temperature of the water used for washing, the amount of water, and the washing time may be the same or different.
　また、本発明においては、水洗を行った後、さらに洗浄液として酸を使用した酸洗浄を行ってもよい。酸洗浄を行った後には、さらに水洗を行うことが好ましく、水洗の条件としては上述した条件と同様とすればよい。 Further, in the present invention, after washing with water, pickling may be further performed using an acid as a cleaning liquid. 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.
（乾燥工程）
　また、上記製造方法においては、上記洗浄工程において洗浄を行った含水クラムに対し、乾燥を行う乾燥工程をさらに備えていてもよい。 (Drying process)
Further, in the above-mentioned manufacturing method, a drying step of drying the water-containing crumbs washed in the above-mentioned washing step may be further provided.
　含水クラムの乾燥方法は、特に限定されず、定法に従えばよいが、たとえば、熱風乾燥機、減圧乾燥機、エキスパンダー乾燥機、ニーダー型乾燥機、スクリュー型押出機などの乾燥機を用いて乾燥する方法などが挙げられる。 The method for drying the water-containing crumb is not particularly limited, and a conventional method may be used. For example, a dryer such as a hot air dryer, a vacuum dryer, an expander dryer, a kneader type dryer, or a screw type extruder is used for drying. How to do it.
　また、含水クラムの乾燥温度は、特に限定されないが、好ましくは８０～２５０℃、より好ましくは９０～２００℃、さらに好ましくは１００～１８０℃である。 The drying temperature of the hydrous crumb is not particularly limited, but is preferably 80 to 250 ° C, more preferably 90 to 200 ° C, and even more preferably 100 to 180 ° C.
　含水クラムについて脱水を行う方法としては、特に限定されないが、遠心分離機、スクイザー、スクリュー型押出機などの脱水機を用いて、含水クラムから水分を排出させる方法が挙げられる。含水クラムの含水率をより低減させることができるという観点より、スクイザー、およびスクリュー型押出機を用いる方法が好ましく、スクリュー型押出機を用いる方法が特に好ましく、スクリュー型押出機を用いることにより、含水クラムの脱水および乾燥を連続工程で行うことができ、これにより、生産性を高めることができる。 The method for dehydrating the water-containing crumb is not particularly limited, and examples thereof include a method of draining water from the water-containing crumb using a dehydrator such as a centrifuge, a squeezer, or a screw type extruder. From the viewpoint that the water content of the water-containing crumb can be further reduced, a method using a squeezer and a screw type extruder is preferable, a method using a screw type extruder is particularly preferable, and a method using a screw type extruder is particularly preferable. The crumbs can be dehydrated and dried in a continuous process, which can increase productivity.
　スクリュー型押出機としては、複数のバレルブロックからなるバレルユニットと、バレルユニットの内部に回転自在に配置された一対のスクリューを備える二軸押出機を好適に用いることができる。 As the screw type extruder, a barrel unit composed of a plurality of barrel blocks and a twin-screw extruder having a pair of screws rotatably arranged inside the barrel unit can be preferably used.
　本発明の製造方法によれば、以上のようにしてカルボキシル基含有アクリルゴムを製造することができる。
　なお、本発明においては、カルボキシル基含有アクリルゴムはクラムの状態にて得てもよいし、ベール化されたゴム、すなわち、カルボキシル基含有アクリルゴムベール（所定形状の塊とされたカルボキシル基含有アクリルゴム）として得てもよい。 According to the production method of the present invention, the carboxyl group-containing acrylic rubber can be produced as described above.
In the present invention, the carboxyl group-containing acrylic rubber may be obtained in the state of a crumb, or a veiled rubber, that is, a carboxyl group-containing acrylic rubber veil (carboxyl group-containing acrylic formed into a mass having a predetermined shape). It may be obtained as rubber).
＜ゴム組成物＞
　本発明のゴム組成物は、上記した本発明のカルボキシル基含有アクリルゴムを含むゴム成分と、架橋剤とを含む。
　ゴム成分中における、本発明のカルボキシル基含有アクリルゴム成分の含有割合は、使用目的に応じて適宜選択すればよいが、好ましくは５１重量％以上であり、より好ましくは７１重量％以上、さらに好ましくは８６重量％以上、特に好ましくは１００重量％（すなわち、ゴム成分として、実質的にカルボキシル基含有アクリルゴム成分のみからなるものを用いた態様）である。 <Rubber composition>
The rubber composition of the present invention contains the above-mentioned rubber component containing the carboxyl group-containing acrylic rubber of the present invention and a cross-linking agent.
The content ratio of the carboxyl group-containing acrylic rubber component of the present invention in the rubber component may be appropriately selected according to the purpose of use, but is preferably 51% by weight or more, more preferably 71% by weight or more, still more preferably. Is 86% by weight or more, particularly preferably 100% by weight (that is, an embodiment in which the rubber component is substantially composed of only a carboxyl group-containing acrylic rubber component).
　ゴム成分を構成する本発明のカルボキシル基含有アクリルゴム以外のゴムとしては、特に限定されないが、本発明のカルボキシル基含有アクリルゴム以外のアクリルゴム、天然ゴム、ポリブタジエンゴム、ポリイソプレンゴム、スチレン－ブタジエンゴム、アクリロニトリル－ブタジエンゴム、シリコンゴム、フッ素ゴム、オレフィン系エラストマー、スチレン系エラストマー、塩化ビニル系エラストマー、ポリエステル系エラストマー、ポリアミド系エラストマー、ポリウレタン系エラストマー、ポリシロキサン系エラストマーなどが挙げられる。 The rubber other than the carboxyl group-containing acrylic rubber of the present invention constituting the rubber component is not particularly limited, but is limited to acrylic rubber other than the carboxyl group-containing acrylic rubber of the present invention, natural rubber, polybutadiene rubber, polyisoprene rubber, and styrene-butadiene. Examples thereof include rubber, acrylic nitrile-butadiene rubber, silicon rubber, fluororubber, olefin-based elastomer, styrene-based elastomer, vinyl chloride-based elastomer, polyester-based elastomer, polyamide-based elastomer, polyurethane-based elastomer, and polysiloxane-based elastomer.
　本発明のカルボキシル基含有アクリルゴム以外のゴムは、１種単独で、または２種以上を併せて使用することができる。本発明のカルボキシル基含有アクリルゴムの形状、および、本発明のカルボキシル基含有アクリルゴム以外のゴムの形状は、特に限定されないが、ベール状、シート状、粉体状等のいずれの形状であってもよい。 The rubber other than the carboxyl group-containing acrylic rubber of the present invention can be used alone or in combination of two or more. The shape of the carboxyl group-containing acrylic rubber of the present invention and the shape of the rubber other than the carboxyl group-containing acrylic rubber of the present invention are not particularly limited, but may be any of veil-like, sheet-like, and powder-like shapes. May be good.
　架橋剤としては、特に限定されないが、たとえば、ジアミン化合物などの多価アミン化合物、およびその炭酸塩；多価エポキシ化合物；などの従来公知の架橋剤を用いることができる。これらの架橋剤は、１種単独で、または２種以上を併せて使用することができる。これらのなかでも、得られるゴム架橋物の耐圧縮永久歪み性をより高めることができるという観点より、多価アミン化合物、およびその炭酸塩を用いることが好ましい。 The cross-linking agent is not particularly limited, but for example, a polyvalent amine compound such as a diamine compound and a conventionally known cross-linking agent such as a carbonate thereof; a polyvalent epoxy compound; can be used. These cross-linking agents can be used alone or in combination of two or more. Among these, it is preferable to use a polyvalent amine compound and a carbonate thereof from the viewpoint of further enhancing the compression set resistance of the obtained rubber crosslinked product.
　多価アミン化合物、およびその炭酸塩としては、特に限定されないが、炭素数４～３０の多価アミン化合物、およびその炭酸塩が好ましい。このような多価アミン化合物、およびその炭酸塩の例としては、脂肪族多価アミン化合物、およびその炭酸塩、ならびに芳香族多価アミン化合物などが挙げられる。 The polyvalent amine compound and its carbonate are not particularly limited, but a polyvalent amine compound having 4 to 30 carbon atoms and a carbonate thereof are preferable. Examples of such polyvalent amine compounds and carbonates thereof include aliphatic polyvalent amine compounds, carbonates thereof, and aromatic polyvalent amine compounds.
　脂肪族多価アミン化合物、およびその炭酸塩としては、特に限定されないが、たとえば、ヘキサメチレンジアミン、ヘキサメチレンジアミンカーバメート、およびＮ，Ｎ’－ジシンナミリデン－１，６－ヘキサンジアミンなどが挙げられる。これらの中でも、ヘキサメチレンジアミンカーバメートが好ましい。 The aliphatic polyvalent amine compound and its carbonate are not particularly limited, and examples thereof include hexamethylenediamine, hexamethylenediamine carbamate, and N, N'-dicinnamylidene-1,6-hexanediamine. Among these, hexamethylenediamine carbamate is preferable.
　芳香族多価アミン化合物としては、特に限定されないが、たとえば、４，４’－メチレンジアニリン、ｐ－フェニレンジアミン、ｍ－フェニレンジアミン、４，４’－ジアミノジフェニルエーテル、３，４’－ジアミノジフェニルエーテル、４，４’－（ｍ－フェニレンジイソプロピリデン）ジアニリン、４，４’－（ｐ－フェニレンジイソプロピリデン）ジアニリン、２，２－ビス〔４－（４－アミノフェノキシ）フェニル〕プロパン、４，４’－ジアミノベンズアニリド、４，４’－ビス（４－アミノフェノキシ）ビフェニル、ｍ－キシリレンジアミン、ｐ－キシリレンジアミン、および１，３，５－ベンゼントリアミンなどが挙げられる。これらの中でも、２，２’－ビス〔４－（４－アミノフェノキシ）フェニル〕プロパンが好ましい。 The aromatic polyvalent amine compound is not particularly limited, and is, for example, 4,4'-methylenedianiline, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether. , 4,4'-(m-phenylenediisopropyridene) dianiline, 4,4'-(p-phenylenediisopropyriden) dianiline, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4 , 4'-diaminobenzanilide, 4,4'-bis (4-aminophenoxy) biphenyl, m-xylylenediamine, p-xylylenediamine, 1,3,5-benzenetriamine and the like. Among these, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane is preferable.
　本発明のゴム組成物中における、架橋剤の含有量は、本発明のカルボキシル基含有アクリルゴムを含むゴム成分１００重量部に対して、好ましくは０．００１～２０重量部、より好ましくは０．１～１０重量部、さらに好ましくは０．１～５重量部、特に好ましくは０．２～４重量部である。架橋剤の含有量を上記範囲とすることにより、ゴム弾性を充分なものとしながら、ゴム架橋物としての機械的強度を優れたものとすることができる。 The content of the cross-linking agent in the rubber composition of the present invention is preferably 0.001 to 20 parts by weight, more preferably 0, with respect to 100 parts by weight of the rubber component containing the carboxyl group-containing acrylic rubber of the present invention. It is 1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and particularly preferably 0.2 to 4 parts by weight. By setting the content of the cross-linking agent in the above range, the mechanical strength of the rubber cross-linked product can be made excellent while the rubber elasticity is sufficient.
　また、本発明のゴム組成物は、さらに架橋促進剤を含有していることが好ましい。架橋促進剤としては、特に限定されないが、架橋剤が多価アミン化合物、またはその炭酸塩である場合には、グアニジン化合物、ジアザビシクロアルケン化合物、イミダゾール化合物、第四級オニウム塩、第三級ホスフィン化合物、脂肪族一価二級アミン化合物、および脂肪族一価三級アミン化合物などを用いることができる。これらのなかでも、グアニジン化合物、ジアザビシクロアルケン化合物、および脂肪族一価二級アミン化合物が好ましく、グアニジン化合物およびジアザビシクロアルケン化合物が特に好ましい。これらの塩基性架橋促進剤は、１種単独で、または２種以上を併せて使用することができる。 Further, it is preferable that the rubber composition of the present invention further contains a cross-linking accelerator. The cross-linking accelerator is not particularly limited, but when the cross-linking agent is a polyvalent amine compound or a carbonate thereof, a guanidine compound, a diazabicycloalkene compound, an imidazole compound, a quaternary onium salt, or a tertiary agent is used. A phosphine compound, an aliphatic monovalent secondary amine compound, an aliphatic monovalent tertiary amine compound and the like can be used. Among these, a guanidine compound, a diazabicycloalkene compound, and an aliphatic monovalent secondary amine compound are preferable, and a guanidine compound and a diazabicycloalkene compound are particularly preferable. These basic cross-linking promoters can be used alone or in combination of two or more.
　グアニジン化合物の具体例としては、１，３－ジ－ｏ－トリルグアニジン、１，３－ジフェニルグアニジンなどが挙げられる。ジアザビシクロアルケン化合物の具体例としては、１，８－ジアザビシクロ［５．４．０］ウンデ－７－セン、１，５－ジアザビシクロ［４．３．０］ノ－５－ネンなどが挙げられる。イミダゾール化合物の具体例としては、２－メチルイミダゾール、２－フェニルイミダゾールなどが挙げられる。第四級オニウム塩の具体例としては、テトラｎ－ブチルアンモニウムブロマイド、オクタデシルトリｎ－ブチルアンモニウムブロマイドなどが挙げられる。第三級ホスフィン化合物の具体例としては、トリフェニルホスフィン、トリ－ｐ－トリルホスフィンなどが挙げられる。 Specific examples of the guanidine compound include 1,3-di-o-tolylguanidine, 1,3-diphenylguanidine and the like. Specific examples of the diazabicycloalkene compound include 1,8-diazabicyclo [5.4.0] unde-7-sen, 1,5-diazabicyclo [4.3.0] no-5-nen and the like. .. Specific examples of the imidazole compound include 2-methylimidazole and 2-phenylimidazole. Specific examples of the quaternary onium salt include tetra n-butylammonium bromide and octadecyltri n-butylammonium bromide. Specific examples of the tertiary phosphine compound include triphenylphosphine and tri-p-tolylphosphine.
　脂肪族一価二級アミン化合物は、アンモニアの水素原子の二つを脂肪族炭化水素基で置換した化合物である。水素原子と置換する脂肪族炭化水素基は、好ましくは炭素数１～３０のものである。脂肪族一価二級アミン化合物の具体例としては、ジメチルアミン、ジエチルアミン、ジプロピルアミン、ジアリルアミン、ジイソプロピルアミン、ジ－ｎ－ブチルアミン、ジ－ｔ－ブチルアミン、ジ－ｓｅｃ－ブチルアミン、ジヘキシルアミン、ジヘプチルアミン、ジオクチルアミン、ジノニルアミン、ジデシルアミン、ジウンデシルアミン、ジドデシルアミン、ジトリデシルアミン、ジテトラデシルアミン、ジペンタデシルアミン、ジセチルアミン、ジ－２－エチルヘキシルアミン、およびジオクタデシルアミンなどが挙げられる。 The aliphatic monovalent secondary amine compound is a compound in which two hydrogen atoms of ammonia are replaced with an aliphatic hydrocarbon group. The aliphatic hydrocarbon group that replaces the hydrogen atom is preferably one having 1 to 30 carbon atoms. Specific examples of the aliphatic monovalent secondary amine compound include dimethylamine, diethylamine, dipropylamine, diallylamine, diisopropylamine, di-n-butylamine, dit-butylamine, di-sec-butylamine, dihexylamine, and dihexylamine. Examples thereof include heptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditridecylamine, ditetradecylamine, dipentadecylamine, disetylamine, di-2-ethylhexylamine, and dioctadecylamine.
　脂肪族一価三級アミン化合物は、アンモニアの三つの水素原子全てを脂肪族炭化水素基で置換した化合物である。水素原子と置換する脂肪族炭化水素基は、好ましくは炭素数１～３０のものである。脂肪族一価三級アミン化合物の具体例としては、トリメチルアミン、トリエチルアミン、トリプロピルアミン、トリアリルアミン、トリイソプロピルアミン、トリ－ｎ－ブチルアミン、トリ－ｔ－ブチルアミン、トリ－ｓｅｃ－ブチルアミン、トリヘキシルアミン、トリヘプチルアミン、トリオクチルアミン、トリノニルアミン、トリデシルアミン、トリウンデシルアミン、およびトリドデシルアミンなどが挙げられる。 The aliphatic monovalent tertiary amine compound is a compound in which all three hydrogen atoms of ammonia are replaced with an aliphatic hydrocarbon group. The aliphatic hydrocarbon group that replaces the hydrogen atom is preferably one having 1 to 30 carbon atoms. Specific examples of the aliphatic monovalent tertiary amine compound include trimethylamine, triethylamine, tripropylamine, triallylamine, triisopropylamine, tri-n-butylamine, tri-t-butylamine, tri-sec-butylamine, and trihexylamine. , Triheptylamine, Trioctylamine, Trinonylamine, Tridecylamine, Triundecylamine, Tridodecylamine and the like.
　本発明のゴム組成物中における、架橋促進剤の含有量は、本発明のカルボキシル基含有アクリルゴムを含むゴム成分１００重量部に対して、好ましくは０．１～１０重量部であり、より好ましくは０．５～７．５重量部、特に好ましくは１～５重量部である。架橋促進剤の含有量を上記範囲とすることにより、得られるゴム架橋物の引張強度および耐圧縮永久歪み性をより向上させることができる。 The content of the crosslinking accelerator in the rubber composition of the present invention is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the rubber component containing the carboxyl group-containing acrylic rubber of the present invention. Is 0.5 to 7.5 parts by weight, particularly preferably 1 to 5 parts by weight. By setting the content of the cross-linking accelerator in the above range, the tensile strength and the compression set resistance of the obtained rubber cross-linked product can be further improved.
　また、本発明のゴム組成物は、さらに充填剤を含有していることが好ましい。充填剤としては、特に限定されないが、補強性充填剤、非補強性充填剤などが挙げられ、これらの中でも、補強性充填剤が好ましい。 Further, it is preferable that the rubber composition of the present invention further contains a filler. The filler is not particularly limited, and examples thereof include a reinforcing filler and a non-reinforcing filler. Among these, a reinforcing filler is preferable.
　補強性充填剤としては、たとえば、ファーネスブラック、アセチレンブラック、サーマルブラック、チャンネルブラック、グラファイトなどのカーボンブラック；湿式シリカ、乾式シリカ、コロイダルシリカなどのシリカ；などが挙げられる。また、非補強性充填剤としては、石英粉末、ケイソウ土などのクレイ、亜鉛華、塩基性炭酸マグネシウム、活性炭酸カルシウム、ケイ酸マグネシウム、ケイ酸アルミニウム、二酸化チタン、タルク、硫酸アルミニウム、硫酸カルシウム、硫酸バリウムなどが挙げられる。 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 non-reinforcing fillers include quartz powder, clay such as silica soil, zinc flower, basic magnesium carbonate, active calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, aluminum sulfate, and calcium sulfate. Examples include barium sulfate.
　これら充填剤は、１種単独で、または２種以上を併せて使用することができる。本発明のゴム組成物中にける、充填剤の含有量は、特に限定されないが、本発明のカルボキシル基含有アクリルゴムを含むゴム成分１００重量部に対して、好ましくは１～２００重量部、より好ましくは１０～１５０重量部、さらに好ましくは２０～１００重量部である。 These fillers can be used alone or in combination of two or more. The content of the filler in the rubber composition of the present invention is not particularly limited, but is preferably 1 to 200 parts by weight, based on 100 parts by weight of the rubber component containing the carboxyl group-containing acrylic rubber of the present invention. It is preferably 10 to 150 parts by weight, more preferably 20 to 100 parts by weight.
　また、本発明のゴム組成物は、上記各成分以外に、ゴム加工分野において通常使用される配合剤を配合することができる。このような配合剤としては、たとえば、老化防止剤；光安定剤；スコーチ防止剤；可塑剤；加工助剤；粘着剤；滑剤；潤滑剤；難燃剤；防黴剤；帯電防止剤；着色剤；架橋遅延剤；などが挙げられる。これらの配合剤の配合量は、本発明の目的や効果を阻害しない範囲であれば特に限定されず、配合目的に応じた量を適宜配合することができる。 Further, in the rubber composition of the present invention, in addition to each of the above components, a compounding agent usually used in the rubber processing field can be blended. Examples of such compounding agents include anti-aging agents; light stabilizers; anti-scorch agents; plasticizers; processing aids; pressure-sensitive adhesives; lubricants; lubricants; flame retardants; fungicides; antistatic agents; coloring agents. ; Crosslink retardant; etc. The blending amount of these blending agents is not particularly limited as long as the purpose and effect of the present invention are not impaired, and an amount suitable for the blending purpose can be appropriately blended.
　本発明のゴム組成物は、上述した本発明のカルボキシル基含有アクリルゴムを含むゴム成分に、架橋剤、およびその他必要に応じて用いられる各種配合剤を配合し、オープンロール、バンバリーミキサー、各種ニーダーなどで混合、混練し、次いで、混練ロールを用いて、さらに混練することなどにより調製される。 In the rubber composition of the present invention, a cross-linking agent and various other compounding agents used as necessary are blended with the above-mentioned rubber component containing the carboxyl group-containing acrylic rubber of the present invention, and an open roll, a Banbury mixer, and various kneaders are blended. It is prepared by mixing and kneading with a kneading roll, and then further kneading with a kneading roll.
　各成分の配合順序は、特に限定されないが、熱で反応や分解しにくい成分を充分に混合した後、熱で反応や分解しやすい成分である架橋剤などを、反応や分解が起こらない温度で短時間に混合することが好ましい。 The blending order of each component is not particularly limited, but after sufficiently mixing the components that are difficult to react or decompose by heat, the cross-linking agent, which is a component that easily reacts or decomposes by heat, is mixed at a temperature at which reaction or decomposition does not occur. It is preferable to mix in a short time.
＜ゴム架橋物＞
　本発明のゴム架橋物は、上述した本発明のゴム組成物を架橋してなるものである。
　本発明のゴム架橋物は、本発明のゴム組成物を用い、所望の形状に対応した成形機、たとえば、押出機、射出成形機、圧縮機、およびロールなどにより成形を行い、加熱することにより架橋反応を行い、ゴム架橋物として形状を固定化することにより製造することができる。この場合においては、予め成形した後に架橋しても、成形と同時に架橋を行ってもよい。成形温度は、通常、１０～２００℃、好ましくは２５～１２０℃である。架橋温度は、通常、１３０～２２０℃、好ましくは１５０～１９０℃であり、架橋時間は、通常、２分～１０時間、好ましくは３分～５時間である。加熱方法としては、プレス加熱、蒸気加熱、オーブン加熱、および熱風加熱などのゴムの架橋に用いられる方法を適宜選択すればよい。 <Rubber cross-linked product>
The rubber crosslinked product of the present invention is obtained by cross-linking the above-mentioned rubber composition of the present invention.
The rubber crosslinked 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 performing 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 120 ° C. The crosslinking temperature is usually 130 to 220 ° C., preferably 150 to 190 ° C., and the crosslinking time is usually 2 minutes to 10 hours, preferably 3 minutes to 5 hours. As 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.
　また、ゴム架橋物の形状、大きさなどによっては、本発明のゴム架橋物は、さらに加熱して二次架橋を行ってもよい。二次架橋は、加熱方法、架橋温度、形状などにより異なるが、好ましくは１～４８時間行う。加熱方法、加熱温度は適宜選択すればよい。 Further, depending on the shape, size, etc. of the rubber crosslinked product, the rubber crosslinked product of the present invention may be further heated for secondary cross-linking. 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.
　そして、このようにして得られる本発明のゴム架橋物は、Ｏ－リング、パッキン、ダイアフラム、オイルシール、シャフトシール、ベアリングシース、メカニカルシール、ウエルヘッドシール、電気・電子機器用シール、空気圧縮機器用シールなどのシール材；シリンダブロックとシリンダヘッドとの連結部に装着されるシリンダヘッドガスケット、ロッカーカバーとシリンダヘッドとの連結部に装着されるロッカーカバーガスケット、オイルパンとシリンダヘッドあるいはトランスミッションケースとの連結部に装着されるオイルパンガスケット、正極、電解質板および負極を備えた単位セルを挟み込む一対のハウジング間に装着された燃料電池セパレーター用ガスケット、ハードディスクドライブのトップカバー用ガスケットなどの各種ガスケット；緩衝材、防振材；電線被覆材；工業用ベルト類；チューブ・ホース類；シート類；等として好適に用いられる。 The rubber crosslinked product of the present invention thus obtained is an O-ring, packing, diaphragm, oil seal, shaft seal, bearing sheath, mechanical seal, well head seal, seal for electric / electronic equipment, air compression equipment. Sealing material such as seals; cylinder head gasket attached to the connection between the cylinder block and the cylinder head, rocker cover gasket attached to the connection between the rocker cover and the cylinder head, oil pan and the cylinder head or transmission case. Various gaskets such as oil pan gaskets mounted on the connecting part of the fuel cell separator, gaskets for fuel cell separators mounted between a pair of housings sandwiching a unit cell equipped with a positive electrode, an electrolyte plate and a negative electrode, and gaskets for the top cover of a hard disk drive; It is suitably used as a cushioning material, a vibration-proof material; an electric wire coating material; an industrial belt, a tube / hose, a sheet, and the like.
　また、本発明のゴム架橋物は、自動車用途に用いられる押し出し成形品および架橋製品として、たとえば、燃料ホース、フィラーネックホース、ベントホース、ベーパーホースなどの燃料油系ホース、ターボエアーホース、ミッションコントロールホース等のエアー系ホース、ラジエターホース、ヒーターホース、ブレーキホース、エアコンホースなどの各種ホース類に好適に用いられる。 Further, the rubber crosslinked product of the present invention is used as an extruded product and a crosslinked product used in automobile applications, for example, fuel hose, filler neck hose, vent hose, vapor hose and other fuel oil hoses, turbo air hose, mission control. It is suitably used for various hoses such as air hoses such as hoses, radiator hoses, heater hoses, brake hoses, and air conditioner hoses.
　以下に、実施例および比較例を挙げて、本発明についてより具体的に説明する。なお、各例中の「部」は、特に断りのない限り、重量基準である。
　各種の物性については、以下の方法に従って評価した。 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 were evaluated according to the following methods.
（１）カルボキシル基含有アクリルゴムのカルボキシル基含有量の測定
　カルボキシル基含有アクリルゴム０．５ｇを秤量し、これをアセトン１００ｍｌに溶解し、次いで、純水１０ｍｌを加えることで、測定用試料を調製した。次いで、測定用試料について、アルコール性ＫＯＨを用いて、中和点まで滴定を行い、滴定に使用したアルコール性ＫＯＨの量から求められるモル当量を算出することで、カルボキシル基含有アクリルゴムのカルボキシル基含有量を、カルボキシル基含有アクリルゴム１００ｇ当たりのカルボキシル基のモル数（単位は、ｍｅｐｈｒ）にて求めた。 (1) Measurement of Carboxyl Group Content of Carboxyl Group-Containing Acrylic Rubber A measurement sample is prepared by weighing 0.5 g of the carboxyl group-containing acrylic rubber, dissolving it in 100 ml of acetone, and then adding 10 ml of pure water. did. Next, the measurement sample is titrated to the neutralization point using alcoholic KOH, and the molar equivalent obtained from the amount of alcoholic KOH used for the titration is calculated to obtain the carboxyl group of the carboxyl group-containing acrylic rubber. The content was determined by the number of moles of carboxyl groups (unit: mephr) per 100 g of carboxyl group-containing acrylic rubber.
（２）カルボキシル基含有アクリルゴムのエタノール水溶液抽出量の測定
　カルボキシル基含有アクリルゴム１．５ｇを秤量し、これを、エタノール水溶液抽出操作を行う前のカルボキシル基含有アクリルゴムの重量Ｗ０とした。次いで、秤量したカルボキシル基含有アクリルゴムを、２ｍｍ角に裁断した後、エタノールを７５体積％および水を２５体積％の割合で含有するエタノール水溶液１５０ｍｌに浸漬させ、次いで、還流式冷却管を備える加熱装置にて、９０℃以上の温度にて１．５時間加熱する操作を２回繰り返し行うことで、エタノール水溶液抽出操作を行った。そして、エタノール水溶液抽出操作を行った後のカルボキシル基含有アクリルゴム試料を乾燥させ、重量を秤量し、これを、エタノール水溶液抽出操作を行った後のカルボキシル基含有アクリルゴムの重量Ｗ１とした。そして、下記式にしたがって、カルボキシル基含有アクリルゴムのエタノール水溶液抽出量を算出した。
　カルボキシル基含有アクリルゴムのエタノール水溶液抽出量（重量％）＝｛（Ｗ０－Ｗ１）／Ｗ０｝×１００ (2) Measurement of the extraction amount of the carboxyl group-containing acrylic rubber in the ethanol aqueous solution 1.5 g of the carboxyl group-containing acrylic rubber was weighed, and this was defined as the weight W0 of the carboxyl group-containing acrylic rubber before the ethanol aqueous solution extraction operation was performed. Next, the weighed carboxyl group-containing acrylic rubber was cut into 2 mm squares, and then immersed in 150 ml of an aqueous ethanol solution containing 75% by volume of ethanol and 25% by volume of water, and then heated with a reflux condenser. The ethanol aqueous solution extraction operation was performed by repeating the operation of heating at a temperature of 90 ° C. or higher for 1.5 hours twice. Then, the carboxyl group-containing acrylic rubber sample after the ethanol aqueous solution extraction operation was dried and weighed, and this was defined as the weight W1 of the carboxyl group - containing acrylic rubber after the ethanol aqueous solution extraction operation. Then, the extraction amount of the aqueous ethanol solution of the carboxyl group-containing acrylic rubber was calculated according to the following formula.
Extraction amount (% by weight) of aqueous ethanol solution of carboxyl group-containing acrylic rubber = {(W 0 -W 1 ) / W 0 } x 100
（３）エタノール水溶液抽出操作後のカルボキシル基含有量の変化量の測定
　上記した（２）カルボキシル基含有アクリルゴムのエタノール水溶液抽出量の測定において得られた、エタノール水溶液抽出操作を行った後のカルボキシル基含有アクリルゴムについて、上記した（１）カルボキシル基含有アクリルゴムのカルボキシル基含有量の測定における方法と同様の方法にて、カルボキシル基含有量を測定した。そして、上記した（１）カルボキシル基含有アクリルゴムのカルボキシル基含有量の測定により得られたカルボキシル基含有量Ａ０（エタノール水溶液抽出操作を行う前のカルボキシル基含有アクリルゴムのカルボキシル基含有量Ａ０）と、エタノール水溶液抽出操作を行った後のカルボキシル基含有アクリルゴムのカルボキシル基含有量Ａ１との差分（Ａ０－Ａ１）を求め、これを、エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量（単位は、ｍｅｐｈｒ）とした。 (3) Measurement of Change in Carboxyl Group Content After Ethanol Aqueous Solution Extraction Operation Carboxyl after Ethanol Aqueous Solution Extraction Operation Obtained in Measurement of Ethanol Aqueous Solution Extraction Amount of (2) Carboxyl Group-Containing Acrylic Rubber For the group-containing acrylic rubber, the carboxyl group content was measured by the same method as in (1) Measuring the carboxyl group content of the carboxyl group-containing acrylic rubber described above. Then, the carboxyl group content A 0 obtained by measuring the carboxyl group content of the above-mentioned (1) carboxyl group-containing acrylic rubber (carboxyl group content A 0 of the carboxyl group-containing acrylic rubber before performing the ethanol aqueous solution extraction operation). ) And the difference (A 0 −A 1 ) between the carboxyl group-containing acrylic rubber and the carboxyl group content A 1 after the ethanol aqueous solution extraction operation was performed, and this was extracted by the ethanol aqueous solution extraction operation. The amount of change in the carboxyl group content (unit: mephr) was used.
（４）ゴム組成物のムーニー粘度（ＭＬ１＋４、１００℃）の測定
　ゴム組成物のムーニー粘度（ＭＬ１＋４、１００℃、コンパウンドムーニー）をＪＩＳ　Ｋ６３００：２０１３に従って測定し、下記基準にて加工性を評価した。下記基準においては、点数が高いほど、加工性に優れる。
　　５点：ゴム組成物のムーニー粘度が、３５以上５５未満
　　４点：ゴム組成物のムーニー粘度が、３０以上３５未満、または、５５以上６５未満
　　３点：ゴム組成物のムーニー粘度が、２５以上３０未満、または、６５以上７５未満
　　２点：ゴム組成物のムーニー粘度が、２０以上２５未満、または、７５以上８５未満
　　１点：ゴム組成物のムーニー粘度が、２０未満、または、８５以上 (4) Measurement of Mooney viscosity (ML1 + 4, 100 ° C.) of rubber composition Mooney viscosity (ML1 + 4, 100 ° C., compound Mooney) of rubber composition was measured according to JIS K6300: 2013, and processability was evaluated according to the following criteria. .. In the following criteria, the higher the score, the better the workability.
5 points: Mooney viscosity of rubber composition is 35 or more and less than 55 4 points: Mooney viscosity of rubber composition is 30 or more and less than 35, or 55 or more and less than 65 3 points: Mooney viscosity of rubber composition is 25 or more Less than 30 or 65 or more and less than 75 2 points: Mooney viscosity of rubber composition is 20 or more and less than 25, or 75 or more and less than 85 1 point: Mooney viscosity of rubber composition is less than 20 or 85 or more
（５）ゴム組成物の表面肌平滑性の測定
　ゴム組成物を、単軸押し出し機およびガーベダイを用いて押出成形し、ＡＳＴＭ　Ｄ２２３０に準じた表面肌平滑性の評価を実施した。表面肌平滑性の評価は、下記の基準で行った。下記基準においては、点数が高いほど、押出加工性に優れる。
　　５点：シート表面が平滑で光沢が有り、かつ、気泡の巻き込みが無い
　　４点：シート表面が平滑で光沢が有り、かつ、気泡の巻き込みがやや有り
　　３点：シート表面が平滑であるが光沢が無い
　　２点：シート表面に凹凸や小皺などの肌荒れ部分が有るが、シートに穴が無い
　　１点：シート表面に凹凸や小皺などの肌荒れ部分が有り、かつ、シートに穴が有り (5) Measurement of Surface Skin Smoothness of Rubber Composition The rubber composition was extruded using a uniaxial extruder and a garve die, and the surface skin smoothness was evaluated according to ASTM D2230. The surface skin smoothness was evaluated according to the following criteria. In the following criteria, the higher the score, the better the extrusion processability.
5 points: The sheet surface is smooth and glossy and there is no air bubble entrainment 4 points: The sheet surface is smooth and glossy and there is some air bubble entrainment 3 points: The sheet surface is smooth but glossy No 2 points: There are rough skin parts such as unevenness and fine wrinkles on the sheet surface, but there are no holes in the sheet 1 point: There are rough skin parts such as unevenness and fine wrinkles on the sheet surface, and there are holes in the sheet
（６）ゴム組成物のロール粘着性の測定
　ロールにより、ゴム組成物を調製した際におけるロールへの粘着性を下記の基準で評価した。下記基準においては、点数が高いほど、加工性に優れる。
　　５点：ロール面への粘着が無く、操作性が良好であった
　　４点：ロール面への粘着が若干発生したが、切返し可能であり、うす通しも可能であった
　　３点：ロール面への粘着が若干発生したが、切返し可能であったものの、うす通しは不可能であった
　　２点：ロール面への粘着が顕著に発生し、切返しも、うす通しも不可能であった
　　１点：ロール面への粘着が顕著に発生し、かつ、ロールの前後両側にゴムが張り付いてしまい、混練不可能であった (6) Measurement of Roll Adhesiveness of Rubber Composition The adhesiveness to the roll when the rubber composition was prepared was evaluated by the following criteria. In the following criteria, the higher the score, the better the workability.
5 points: No adhesion to the roll surface and good operability 4 points: Some adhesion to the roll surface occurred, but it was possible to cut back and thinly pass through 3 points: To the roll surface Adhesion occurred slightly, but it was possible to turn it back, but it was not possible to pass it through. 2 points: Adhesion to the roll surface occurred remarkably, and it was impossible to turn it back and pass it through. 1 point. : Adhesion to the roll surface occurred remarkably, and rubber stuck to both front and rear sides of the roll, making kneading impossible.
（７）加工性の総合評価
　上記（４）ゴム組成物のムーニー粘度（ＭＬ１＋４、１００℃）の測定、（５）ゴム組成物の表面肌平滑性の測定、および（６）ゴム組成物のロール粘着性の測定の結果の平均値を算出し、４点以上である場合に、加工性が良好であると判断した。 (7) Comprehensive evaluation of processability (4) Measurement of Mooney viscosity (ML1 + 4, 100 ° C.) of the rubber composition, (5) Measurement of surface skin smoothness of the rubber composition, and (6) Roll of the rubber composition The average value of the results of the adhesiveness measurement was calculated, and when it was 4 points or more, it was judged that the processability was good.
（８）圧縮永久歪み率の測定
　ゴム組成物を、金型を用いて、温度１７０℃で２０分間プレスすることにより一次架橋し、直径２９ｍｍ、高さ１２．７ｍｍの円柱型の一次架橋物を得て、次いで、得られた一次架橋物を、ギヤー式オーブンにて、さらに１７０℃、４時間の条件で加熱して二次架橋させることにより、円柱状のゴム架橋物を得た。そして、得られたゴム架橋物を用いて、ＪＩＳ　Ｋ６２６２：２００６に従い、ゴム架橋物を２５％圧縮させた状態で、１７５℃の環境下に７０時間置いた後、圧縮永久歪み率を測定した。この値が小さいほど、耐圧縮永久歪み性に優れる。 (8) Measurement of Compressive Permanent Strain Rate The rubber composition is primarily crosslinked by pressing it at a temperature of 170 ° C. for 20 minutes using a mold to obtain a cylindrical primary crosslinked product having a diameter of 29 mm and a height of 12.7 mm. Then, the obtained primary crosslinked product was further heated in a gear type oven at 170 ° C. for 4 hours for secondary cross-linking to obtain a columnar rubber crosslinked product. Then, using the obtained rubber crosslinked product, the rubber crosslinked product was placed in an environment of 175 ° C. for 70 hours in a state of being compressed by 25% according to JIS K6262: 2006, and then the compression permanent strain rate was measured. The smaller this value, the better the compression resistance and permanent strain resistance.
［実施例１］
（カルボキシル基含有アクリルゴム（Ａ－１）の製造）
・単量体乳化液調製工程
　ホモミキサーを備えた混合容器に、純水４８．２部、アクリル酸エチル４５部、アクリル酸ｎ－ブチル５３．２部、フマル酸モノｎ－ブチル１．８部、アニオン性界面活性剤としてのラウリル硫酸ナトリウム（商品名「エマール２ＦＧ」、花王社製）１．５部、ノニオン性界面活性剤としてのポリオキシエチレンドデシルエーテル（商品名「エマルゲン１０５」、ＧＰＣ測定によるポリスチレン換算での重量平均分子量：約１５００、花王社製）０．３部、および、エチレンジアミン四酢酸（ＥＤＴＡ）０．０１部を仕込み、攪拌することで、単量体乳化液１５０部を得た。 [Example 1]
(Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-1))
Monomer emulsion preparation step In a mixing container equipped with a homomixer, 48.2 parts of pure water, 45 parts of ethyl acrylate, 53.2 parts of n-butyl acrylate, 1.8 parts of mono-n-butyl fumarate. , Sodium lauryl sulfate as an anionic surfactant (trade name "Emar 2FG", manufactured by Kao Co., Ltd.) 1.5 parts, Polyoxyethylene dodecyl ether as a nonionic surfactant (trade name "Emargen 105", GPC measurement) Weight average molecular weight in terms of polystyrene: Approximately 1500, manufactured by Kao Co., Ltd.) 0.3 parts and 0.01 part of ethylenediamine tetraacetic acid (EDTA) are charged and stirred to obtain 150 parts of monomeric emulsion. rice field.
・初期重合工程
　次いで、温度計、攪拌装置を備えた重合反応槽に、純水１５０部、および、上記にて得られた単量体乳化液１５．０部を投入し、窒素気流下で温度１５℃まで冷却した。次いで、重合反応槽中に、硫酸第一鉄（還元剤）０．００１５部、ホルムアルデヒドスルホキシル酸ナトリウム（還元剤）０．０３０部、および、クメンハイドロパーオキサイド（過酸化物）０． ００５部を滴下し反応を開始させ、反応を１時間継続させた。 -Initial polymerization step Next, 150 parts of pure water and 15.0 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 increased under a nitrogen stream. It was cooled to 15 ° C. Next, 0.0015 parts of ferrous sulfate (reducing agent), 0.030 parts of sodium formaldehyde sulfoxylate (reducing agent), and cumene hydroperoxide (peroxide) 0. The reaction was started by dropping 005 parts, and the reaction was continued for 1 hour.
・単量体乳化液滴下工程
　次いで、上記反応を１時間行った後、重合反応槽中に、上記にて得られた単量体乳化液１３５部（初期重合工程で使用した分を除いた残部）、硫酸第一鉄０．００３部、ホルムアルデヒドスルホキシル酸ナトリウム０ ．２０部、および、クメンハイドロパーオキサイド０．００８部を９時間かけて連続的に滴下した。なお、単量体乳化液と、還元剤と、過酸化物とは、それぞれ別々の滴下装置より滴下した。 -Step below the monomer emulsifying droplets Next, after the above reaction was carried out for 1 hour, 135 parts of the monomer emulsifying solution obtained above (the balance excluding the portion used in the initial polymerization step) was placed in the polymerization reaction tank. ), 0.003 part of ferrous sulfate, sodium formaldehyde sulfoxylate 0. 20 parts and 0.008 parts of cumene hydroperoxide were continuously added dropwise over 9 hours. The monomeric emulsion, the reducing agent, and the peroxide were added dropwise from separate dropping devices.
・後反応工程
　そして、単量体乳化液滴下工程における滴下終了後（単量体乳化液滴下工程における滴下終了時点の重合転化率は８８．７％）、重合反応槽内の温度を３５℃に昇温し、温度を３５℃に保った状態にて、硫酸第一鉄０．００３部、ホルムアルデヒドスルホキシル酸ナトリウム０．００５部、および、クメンハイドロパーオキサイド０．０３部を添加し、１時間反応を継続することで後反応を行い、重合転化率が９８．２％となった時点で、重合停止剤としてのハイドロキノンを添加して重合反応を停止し、乳化重合液を得た。 -Post-reaction step Then, after the completion of the dropping in the monomer emulsifying droplet lowering step (the polymerization conversion rate at the completion of the dropping in the monomer emulsifying droplet lowering step is 88.7%), the temperature in the polymerization reaction tank is set to 35 ° C. While the temperature was raised and the temperature was maintained at 35 ° C., 0.003 part of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of cumene hydroperoxide were added for 1 hour. The post-reaction was carried out by continuing the reaction, and when the polymerization conversion rate reached 98.2%, hydroquinone as a polymerization terminator was added to terminate the polymerization reaction to obtain an emulsified polymerization solution.
・凝固工程、洗浄工程、乾燥工程
　次いで、得られた乳化重合液を凝固槽に移し、この乳化重合液１００部に対して、工業用水６０部を添加して、８５℃に昇温した後、温度８５℃にて、混合液を撹拌しながら、凝固剤としての硫酸マグネシウム１０部を連続的に添加することで、重合体を凝固させ濾別することで、含水クラムを得た。
　次いで、上記にて得られた含水クラムの固形分１００部に対し、工業用水３０００部を添加し、凝固槽内で、室温、５分間撹拌した後、凝固槽から水分を排出させることで、含水クラムの水洗を行った。そして、水洗後の含水クラムを１１０℃の熱風乾燥機で１時間乾燥させることにより、固形状のカルボキシル基含有アクリルゴム（Ａ－１）を得た。 -Coagulation step, washing step, drying step Next, the obtained emulsified polymer solution is transferred to a coagulation tank, 60 parts of industrial water is added to 100 parts of this emulsified polymer solution, and the temperature is raised to 85 ° C. A hydrous crumb was obtained by continuously adding 10 parts of magnesium sulfate as a coagulant while stirring the mixed solution at a temperature of 85 ° C. to coagulate the polymer and separate it by filtration.
Next, 3000 parts of industrial water was added to 100 parts of the solid content of the water-containing crumb obtained above, and the mixture was stirred at room temperature for 5 minutes in the coagulation tank, and then the water was discharged from the coagulation tank to contain water. The crumb was washed with water. Then, the hydrous crumb after washing with water was dried in a hot air dryer at 110 ° C. for 1 hour to obtain a solid carboxyl group-containing acrylic rubber (A-1).
　そして、得られたカルボキシル基含有アクリルゴム（Ａ－１）について、上記方法にしたがって、カルボキシル基含有量の測定、エタノール水溶液抽出量の測定、およびエタノール水溶液抽出操作後のカルボキシル基含有量の変化量の測定を行った結果を表１に示す。
　なお、得られたカルボキシル基含有アクリルゴム（Ａ－１）のエタノール水溶液抽出成分は、分子量が５０００以上である成分が８５重量％以上であり、そのため、エタノール水溶液抽出量は、比較的低分子量である重合体成分を主とするものであり、残部は、重合副資材等であると判断することができるものであった（後述する実施例２～５、比較例１～５においても同様）。
　また、得られたカルボキシル基含有アクリルゴム（Ａ－１）の単量体組成は、使用した単量体の割合とほぼ等しいものであった（後述する実施例２～５、比較例１～５においても同様）。 Then, with respect to the obtained carboxyl group-containing acrylic rubber (A-1), the amount of change in the carboxyl group content after the measurement of the carboxyl group content, the measurement of the ethanol aqueous solution extraction amount, and the ethanol aqueous solution extraction operation according to the above method. The results of the measurement are shown in Table 1.
The obtained ethanol aqueous solution extraction component of the carboxyl group-containing acrylic rubber (A-1) has a molecular weight of 5000 or more in an amount of 85% by weight or more. Therefore, the ethanol aqueous solution extraction amount has a relatively low molecular weight. It was mainly composed of a certain polymer component, and the balance could be determined to be a polymerization auxiliary material or the like (the same applies to Examples 2 to 5 and Comparative Examples 1 to 5 described later).
Further, the monomer composition of the obtained carboxyl group-containing acrylic rubber (A-1) was almost equal to the ratio of the monomers used (Examples 2 to 5 and Comparative Examples 1 to 5 described later). The same applies to).
（ゴム組成物の調製）
　バンバリーミキサーを用いて、上記にで得られたカルボキシル基含有アクリルゴム（Ａ－１）１００部に、ＦＥＦカーボンブラック（商品名「シーストＳＯ」、東海カーボン社製、充填剤、「シースト」は登録商標）６０部、ステアリン酸２部、エステル系ワックス（商品名「グレッグＧ－８２０５」、大日本インキ化学工業社製、滑剤）１部、４，４ '－ビス（α，α－ジメチルベンジル）ジフェニルアミン（商品名「ノクラックＣＤ」、大内新興化学工業社製、老化防止剤、「ノクラック」は登録商標）２部を添加して、８０℃で５分間混合した。次いで、得られた混合物を５０℃のロールに移して、ヘキサメチレンジアミンカルバメート（商品名「Ｄｉａｋ＃１」、デュポンエラストマー社製、架橋剤）０．６０部、および１，８－ジアザビシクロ［５．４．０］ウンデカ－７－エン（商品名「ＲＨＥＮＯＧＲＡＮ ＸＬＡ－６０」、ランクセス社製、架橋促進剤）２部を配合して、混練することにより、ゴム組成物を得た。
　そして、得られたゴム組成物を用いて、上記した方法にしたがって、加工性の評価および圧縮永久歪み率の測定を行った。結果を表１に示す。 (Preparation of rubber composition)
Using a Banbury mixer, FEF carbon black (trade name "Ester SO", manufactured by Tokai Carbon Co., Ltd., filler, "Ester" is registered in 100 parts of the carboxyl group-containing acrylic rubber (A-1) obtained above. Trademark) 60 parts, stearic acid 2 parts, ester wax (trade name "Greg G-8205", manufactured by Dainippon Ink and Chemicals Co., Ltd., lubricant) 1 part, 4,4'-bis (α, α-dimethylbenzyl) Two parts of diphenylamine (trade name "Nocrack CD", manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., anti-aging agent, "Nocrack" is a registered trademark) were added and mixed at 80 ° C. for 5 minutes. Then, the obtained mixture was transferred to a roll at 50 ° C., and 0.60 part of hexamethylenediamine carbamate (trade name “Diak # 1”, manufactured by DuPont Elastomer, a cross-linking agent), and 1,8-diazabicyclo [5. 4.0] Undeca-7-en (trade name "RHENOGRAN XLA-60", manufactured by LANXESS, a cross-linking accelerator) was blended and kneaded to obtain a rubber composition.
Then, using the obtained rubber composition, the processability was evaluated and the compression set was measured according to the above method. The results are shown in Table 1.
［実施例２］
（カルボキシル基含有アクリルゴム（Ａ－２）の製造）
　単量体乳化液調製工程における、アクリル酸エチルの配合量を４２．５部に、アクリル酸ｎ－ブチルの配合量を５０．７部にそれぞれ変更したこと、初期重合工程および単量体乳化液滴下工程における、硫酸第一鉄、ホルムアルデヒドスルホキシル酸ナトリウム、および、クメンハイドロパーオキサイドの使用量を表１に示す量としたこと以外は、実施例１と同様にして、単量体乳化液調製工程、初期重合工程および単量体乳化液滴下工程を行った。 [Example 2]
(Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-2))
The compounding amount of ethyl acrylate was changed to 42.5 parts and the compounding amount of n-butyl acrylate was changed to 50.7 parts in the monomer emulsion preparation step, the initial polymerization step and the monomer emulsion. Preparation of monomeric emulsion was prepared in the same manner as in Example 1 except that the amounts of ferrous sulfate, sodium formaldehyde sulfoxylate, and cumene hydroperoxide used in the dropping step were the amounts shown in Table 1. A step, an initial polymerization step and a monomer emulsifying droplet lowering step were performed.
　次いで、単量体乳化液滴下工程における滴下終了後（単量体乳化液滴下工程における滴下終了時点の重合転化率は９２．０％）、重合反応槽内の温度を３５℃に昇温し、温度を３５℃に保った状態にて、アクリル酸エチル２．５部、アクリル酸ｎ－ブチル２．５部、硫酸第一鉄０．００３部、ホルムアルデヒドスルホキシル酸ナトリウム０．００５部、および、クメンハイドロパーオキサイド０．０３部を添加し、１時間反応を継続することで後反応を行い、重合転化率が９８．１％となった時点で、重合停止剤としてのハイドロキノンを添加して重合反応を停止し、乳化重合液を得た。そして、実施例１と同様にして、凝固工程、洗浄工程、および乾燥工程を行うことで、固形状のカルボキシル基含有アクリルゴム（Ａ－２）を得て、同様に各測定を行った。結果を表１に示す。 Next, after the completion of the dropping in the step below the monomer emulsifying droplet (the polymerization conversion rate at the end of the dropping in the step below the monomer emulsifying droplet was 92.0%), the temperature in the polymerization reaction tank was raised to 35 ° C. Keeping the temperature at 35 ° C., 2.5 parts of ethyl acrylate, 2.5 parts of n-butyl acrylate, 0.003 parts of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of Kumen hydroperoxide was added and the reaction was continued for 1 hour to carry out the post-reaction. When the polymerization conversion rate reached 98.1%, hydroquinone as a polymerization terminator was added for polymerization. The reaction was stopped to obtain an emulsified polymer solution. Then, the solidification step, the washing step, and the drying step were carried out in the same manner as in Example 1 to obtain a solid carboxyl group-containing acrylic rubber (A-2), and each measurement was carried out in the same manner. The results are shown in Table 1.
（ゴム組成物の調製）
　上記にて得られたカルボキシル基含有アクリルゴム（Ａ－２）を用いた以外は、実施例１と同様にして、ゴム組成物を調製し、同様に各測定を行った。結果を表１に示す。 (Preparation of rubber composition)
A rubber composition was prepared in the same manner as in Example 1 except that the carboxyl group-containing acrylic rubber (A-2) obtained above was used, and each measurement was carried out in the same manner. The results are shown in Table 1.
［実施例３］
（カルボキシル基含有アクリルゴム（Ａ－３）の製造）
　単量体乳化液調製工程における、フマル酸モノｎ－ブチルの配合量を１．４４部に変更したこと、初期重合工程において、別途、フマル酸モノｎ－ブチル０．３６部をさらに配合したこと、さらには、初期重合工程および単量体乳化液滴下工程における、硫酸第一鉄、ホルムアルデヒドスルホキシル酸ナトリウム、および、クメンハイドロパーオキサイドの使用量を表１に示す量としたこと以外は、実施例１と同様にして、単量体乳化液調製工程、初期重合工程および単量体乳化液滴下工程を行った。 [Example 3]
(Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-3))
The amount of mono n-butyl fumarate to be blended was changed to 1.44 parts in the monomer emulsion preparation step, and 0.36 parts of mono n-butyl fumarate was separately blended in the initial polymerization step. Further, it was carried out except that the amounts of ferrous sulfate, sodium formaldehyde sulfoxylate, and cumene hydroperoxide used in the initial polymerization step and the monomer emulsification droplet lowering step were set to the amounts shown in Table 1. In the same manner as in Example 1, a monomer emulsion preparation step, an initial polymerization step, and a monomer emulsifying droplet lowering step were performed.
　次いで、単量体乳化液滴下工程における滴下終了後（単量体乳化液滴下工程における滴下終了時点の重合転化率は８３．１％）、重合反応槽内の温度を３５℃に昇温し、温度を３５℃に保った状態にて、硫酸第一鉄０．００３部、ホルムアルデヒドスルホキシル酸ナトリウム０．００５部、および、クメンハイドロパーオキサイド０．０３部を添加し、１時間反応を継続することで後反応を行い、重合転化率が９７．５％となった時点で、重合停止剤としてのハイドロキノンを添加して重合反応を停止し、乳化重合液を得た。そして、実施例１と同様にして、凝固工程、洗浄工程、および乾燥工程を行うことで、固形状のカルボキシル基含有アクリルゴム（Ａ－３）を得て、同様に各測定を行った。結果を表１に示す。 Next, after the completion of the dropping in the step below the monomer emulsifying droplet (the polymerization conversion rate at the end of the dropping in the step below the monomer emulsifying droplet was 83.1%), the temperature in the polymerization reaction tank was raised to 35 ° C. While keeping the temperature at 35 ° C., 0.003 part of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of cumene hydroperoxide are added, and the reaction is continued for 1 hour. Therefore, the post-reaction was carried out, and when the polymerization conversion rate reached 97.5%, hydroquinone as a polymerization terminator was added to terminate the polymerization reaction to obtain an emulsified polymerization solution. Then, the solidification step, the washing step, and the drying step were carried out in the same manner as in Example 1 to obtain a solid carboxyl group-containing acrylic rubber (A-3), and each measurement was carried out in the same manner. The results are shown in Table 1.
（ゴム組成物の調製）
　上記にて得られたカルボキシル基含有アクリルゴム（Ａ－３）を用いた以外は、実施例１と同様にして、ゴム組成物を調製し、同様に各測定を行った。結果を表１に示す。 (Preparation of rubber composition)
A rubber composition was prepared in the same manner as in Example 1 except that the carboxyl group-containing acrylic rubber (A-3) obtained above was used, and each measurement was carried out in the same manner. The results are shown in Table 1.
［実施例４］
（カルボキシル基含有アクリルゴム（Ａ－４）の製造）
　実施例１と同様にして、単量体乳化液調製工程、初期重合工程および単量体乳化液滴下工程を行った後（単量体乳化液滴下工程における滴下終了時点の重合転化率は８９．２％）、重合反応槽内の温度を３５℃に昇温し、温度を３５℃に保った状態にて、ｔ－ドデシルメルカプタン０．０１部を添加し、４時間反応を継続することで後反応を行い、重合転化率が９５．３％となった時点で、重合停止剤としてのハイドロキノンを添加して重合反応を停止し、乳化重合液を得た。そして、実施例１と同様にして、凝固工程、洗浄工程、および乾燥工程を行うことで、固形状のカルボキシル基含有アクリルゴム（Ａ－４）を得て、同様に各測定を行った。結果を表１に示す。 [Example 4]
(Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-4))
After performing the monomer emulsion preparation step, the initial polymerization step and the monomer emulsifying droplet lowering step in the same manner as in Example 1, the polymerization conversion rate at the end of the dropping in the monomer emulsifying droplet lowering step is 89. 2%), raise the temperature in the polymerization reaction tank to 35 ° C, add 0.01 part of t-dodecyl mercaptan while keeping the temperature at 35 ° C, and continue the reaction for 4 hours. The reaction was carried out, and when the polymerization conversion rate reached 95.3%, hydroquinone as a polymerization terminator was added to terminate the polymerization reaction to obtain an emulsified polymer solution. Then, the solidification step, the washing step, and the drying step were carried out in the same manner as in Example 1 to obtain a solid carboxyl group-containing acrylic rubber (A-4), and each measurement was carried out in the same manner. The results are shown in Table 1.
（ゴム組成物の調製）
　上記にて得られたカルボキシル基含有アクリルゴム（Ａ－４）を用いた以外は、実施例１と同様にして、ゴム組成物を調製し、同様に各測定を行った。結果を表１に示す。 (Preparation of rubber composition)
A rubber composition was prepared in the same manner as in Example 1 except that the carboxyl group-containing acrylic rubber (A-4) obtained above was used, and each measurement was carried out in the same manner. The results are shown in Table 1.
［実施例５］
（カルボキシル基含有アクリルゴム（Ａ－５）の製造）
　単量体乳化液調製工程における、アクリル酸エチルの配合量を５５部に、アクリル酸ｎ－ブチルの配合量を４３．２部にそれぞれ変更した以外は、実施例１と同様にして、単量体乳化液調製工程、初期重合工程および単量体乳化液滴下工程を行った。 [Example 5]
(Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-5))
In the monomer emulsion preparation step, the single amount was the same as in Example 1 except that the blending amount of ethyl acrylate was changed to 55 parts and the blending amount of n-butyl acrylate was changed to 43.2 parts. A body emulsion preparation step, an initial polymerization step, and a monomer emulsifying droplet lowering step were performed.
　次いで、単量体乳化液滴下工程を行った後（単量体乳化液滴下工程における滴下終了時点の重合転化率は８８．０％）、重合反応槽内の温度を３５℃に昇温し、温度を３５℃に保った状態にて、硫酸第一鉄０．００３部、ホルムアルデヒドスルホキシル酸ナトリウム０．００５部、および、クメンハイドロパーオキサイド０．０３部を添加し、１時間反応を継続することで後反応を行い、重合転化率が９７．９％となった時点で、重合停止剤としてのハイドロキノンを添加して重合反応を停止し、乳化重合液を得た。そして、実施例１と同様にして、凝固工程、洗浄工程、および乾燥工程を行うことで、固形状のカルボキシル基含有アクリルゴム（Ａ－５）を得て、同様に各測定を行った。結果を表１に示す。 Next, after performing the monomer emulsification droplet lowering step (the polymerization conversion rate at the end of the dropping in the monomer emulsifying droplet lowering step is 88.0%), the temperature in the polymerization reaction tank was raised to 35 ° C. While keeping the temperature at 35 ° C., 0.003 part of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of cumene hydroperoxide are added, and the reaction is continued for 1 hour. Therefore, a post-reaction was carried out, and when the polymerization conversion rate reached 97.9%, hydroquinone as a polymerization terminator was added to terminate the polymerization reaction to obtain an emulsified polymerization solution. Then, the solidification step, the washing step, and the drying step were carried out in the same manner as in Example 1 to obtain a solid carboxyl group-containing acrylic rubber (A-5), and each measurement was carried out in the same manner. The results are shown in Table 1.
（ゴム組成物の調製）
　上記にて得られたカルボキシル基含有アクリルゴム（Ａ－５）を用いた以外は、実施例１と同様にして、ゴム組成物を調製し、同様に各測定を行った。結果を表１に示す。 (Preparation of rubber composition)
A rubber composition was prepared in the same manner as in Example 1 except that the carboxyl group-containing acrylic rubber (A-5) obtained above was used, and each measurement was carried out in the same manner. The results are shown in Table 1.
［比較例１］
（カルボキシル基含有アクリルゴム（Ａ－６）の製造）
　初期重合工程および単量体乳化液滴下工程における、硫酸第一鉄、ホルムアルデヒドスルホキシル酸ナトリウム、および、クメンハイドロパーオキサイドの使用量を表１に示す量としたこと以外は、実施例１と同様にして、単量体乳化液調製工程、初期重合工程および単量体乳化液滴下工程を行った。 [Comparative Example 1]
(Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-6))
Same as in Example 1 except that the amounts of ferrous sulfate, sodium formaldehyde sulfoxylate, and cumene hydroperoxide used in the initial polymerization step and the step below the monomer emulsified droplet were set to the amounts shown in Table 1. Then, a monomer emulsion preparation step, an initial polymerization step, and a monomer emulsifying droplet lowering step were performed.
　次いで、単量体乳化液滴下工程を行った後（単量体乳化液滴下工程における滴下終了時点の重合転化率は９３．２％）、重合反応槽内の温度を３５℃に昇温し、温度を３５℃に保った状態にて、硫酸第一鉄０．００３部、ホルムアルデヒドスルホキシル酸ナトリウム０．００５部、および、クメンハイドロパーオキサイド０．０３部を添加し、１時間反応を継続することで後反応を行い、重合転化率が９７．８％となった時点で、重合停止剤としてのハイドロキノンを添加して重合反応を停止し、乳化重合液を得た。そして、実施例１と同様にして、凝固工程、洗浄工程、および乾燥工程を行うことで、固形状のカルボキシル基含有アクリルゴム（Ａ－６）を得て、同様に各測定を行った。結果を表１に示す。 Next, after performing the monomer emulsifying droplet lowering step (the polymerization conversion rate at the end of the dropping in the monomer emulsifying droplet lowering step is 93.2%), the temperature in the polymerization reaction tank was raised to 35 ° C. While keeping the temperature at 35 ° C., 0.003 part of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of cumene hydroperoxide are added, and the reaction is continued for 1 hour. Therefore, the post-reaction was carried out, and when the polymerization conversion rate reached 97.8%, hydroquinone as a polymerization terminator was added to terminate the polymerization reaction to obtain an emulsified polymerization solution. Then, the solidification step, the washing step, and the drying step were carried out in the same manner as in Example 1 to obtain a solid carboxyl group-containing acrylic rubber (A-6), and each measurement was carried out in the same manner. The results are shown in Table 1.
（ゴム組成物の調製）
　上記にて得られたカルボキシル基含有アクリルゴム（Ａ－６）を用いた以外は、実施例１と同様にして、ゴム組成物を調製し、同様に各測定を行った。結果を表１に示す。 (Preparation of rubber composition)
A rubber composition was prepared in the same manner as in Example 1 except that the carboxyl group-containing acrylic rubber (A-6) obtained above was used, and each measurement was carried out in the same manner. The results are shown in Table 1.
［比較例２］
（カルボキシル基含有アクリルゴム（Ａ－７）の製造）
　初期重合工程および単量体乳化液滴下工程における、硫酸第一鉄、ホルムアルデヒドスルホキシル酸ナトリウム、および、クメンハイドロパーオキサイドの使用量を表１に示す量としたこと以外は、実施例１と同様にして、単量体乳化液調製工程、初期重合工程および単量体乳化液滴下工程を行った。 [Comparative Example 2]
(Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-7))
Same as in Example 1 except that the amounts of ferrous sulfate, sodium formaldehyde sulfoxylate, and cumene hydroperoxide used in the initial polymerization step and the step below the monomer emulsified droplet were set to the amounts shown in Table 1. Then, a monomer emulsion preparation step, an initial polymerization step, and a monomer emulsifying droplet lowering step were performed.
　次いで、単量体乳化液滴下工程を行った後（単量体乳化液滴下工程における滴下終了時点の重合転化率は８３．２％）、重合反応槽内の温度を３５℃に昇温し、温度を３５℃に保った状態にて、硫酸第一鉄０．００３部、ホルムアルデヒドスルホキシル酸ナトリウム０．００５部、および、クメンハイドロパーオキサイド０．０３部を添加し、１時間反応を継続することで後反応を行い、重合転化率が９８．１％となった時点で、重合停止剤としてのハイドロキノンを添加して重合反応を停止し、乳化重合液を得た。そして、実施例１と同様にして、凝固工程、洗浄工程、および乾燥工程を行うことで、固形状のカルボキシル基含有アクリルゴム（Ａ－７）を得て、同様に各測定を行った。結果を表１に示す。 Next, after performing the monomer emulsifying droplet lowering step (the polymerization conversion rate at the end of the dropping in the monomer emulsifying droplet lowering step is 83.2%), the temperature in the polymerization reaction tank was raised to 35 ° C. While keeping the temperature at 35 ° C., 0.003 part of ferrous sulfate, 0.005 part of sodium formaldehyde sulfoxylate, and 0.03 part of cumene hydroperoxide are added, and the reaction is continued for 1 hour. Therefore, the post-reaction was carried out, and when the polymerization conversion rate reached 98.1%, hydroquinone as a polymerization terminator was added to terminate the polymerization reaction to obtain an emulsified polymerization solution. Then, the solidification step, the washing step, and the drying step were carried out in the same manner as in Example 1 to obtain a solid carboxyl group-containing acrylic rubber (A-7), and each measurement was carried out in the same manner. The results are shown in Table 1.
（ゴム組成物の調製）
　上記にて得られたカルボキシル基含有アクリルゴム（Ａ－７）を用いた以外は、実施例１と同様にして、ゴム組成物を調製し、同様に各測定を行った。結果を表１に示す。 (Preparation of rubber composition)
A rubber composition was prepared in the same manner as in Example 1 except that the carboxyl group-containing acrylic rubber (A-7) obtained above was used, and each measurement was carried out in the same manner. The results are shown in Table 1.
［比較例３］
（カルボキシル基含有アクリルゴム（Ａ－８）の製造）
　初期重合工程および単量体乳化液滴下工程における、硫酸第一鉄、ホルムアルデヒドスルホキシル酸ナトリウム、および、クメンハイドロパーオキサイドの使用量を表１に示す量としたこと以外は、実施例１と同様にして、単量体乳化液調製工程、初期重合工程および単量体乳化液滴下工程を行った。 [Comparative Example 3]
(Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-8))
Same as in Example 1 except that the amounts of ferrous sulfate, sodium formaldehyde sulfoxylate, and cumene hydroperoxide used in the initial polymerization step and the step below the monomer emulsified droplet were set to the amounts shown in Table 1. Then, a monomer emulsion preparation step, an initial polymerization step, and a monomer emulsifying droplet lowering step were performed.
　次いで、単量体乳化液滴下工程を行った後（単量体乳化液滴下工程における滴下終了時点の重合転化率は８８．６％）、重合反応槽内の温度を３５℃に昇温し、温度を３５℃に保った状態にて、１時間反応を継続することで後反応を行い、重合転化率が９４．０％となった時点で、重合停止剤としてのハイドロキノンを添加して重合反応を停止し、乳化重合液を得た。なお、後反応開始時の重合反応系中における、そして、実施例１と同様にして、凝固工程、洗浄工程、および乾燥工程を行うことで、固形状のカルボキシル基含有アクリルゴム（Ａ－８）を得て、同様に各測定を行った。結果を表１に示す。 Next, after performing the monomer emulsification droplet lowering step (the polymerization conversion rate at the end of the dropping in the monomer emulsifying droplet lowering step is 88.6%), the temperature in the polymerization reaction tank was raised to 35 ° C. The post-reaction was carried out by continuing the reaction for 1 hour while keeping the temperature at 35 ° C., and when the polymerization conversion rate reached 94.0%, hydroquinone as a polymerization terminator was added to carry out the polymerization reaction. Was stopped to obtain an emulsion polymerization solution. In the polymerization reaction system at the start of the post-reaction, and by performing the solidification step, the washing step, and the drying step in the same manner as in Example 1, the solid carboxyl group-containing acrylic rubber (A-8). And each measurement was performed in the same manner. The results are shown in Table 1.
（ゴム組成物の調製）
　上記にて得られたカルボキシル基含有アクリルゴム（Ａ－８）を用いた以外は、実施例１と同様にして、ゴム組成物を調製し、同様に各測定を行った。結果を表１に示す。 (Preparation of rubber composition)
A rubber composition was prepared in the same manner as in Example 1 except that the carboxyl group-containing acrylic rubber (A-8) obtained above was used, and each measurement was carried out in the same manner. The results are shown in Table 1.
［比較例４］
（カルボキシル基含有アクリルゴム（Ａ－９）の製造）
　温度計、攪拌装置を備えた重合反応槽に、純水２００部、および、アクリル酸エチル４５部、アクリル酸ｎ－ブチル５３．２部、フマル酸モノｎ－ブチル１．８部、アニオン性界面活性剤としてのラウリル硫酸ナトリウム（商品名「エマール２ＦＧ」、花王社製）１．５部、およびノニオン性界面活性剤としてのポリオキシエチレンドデシルエーテル（商品名「エマルゲン１０５」、花王社製）０．３部、エチレンジアミン四酢酸（ＥＤＴＡ）を０．０１部仕込み、攪拌し、窒素気流下で温度１５℃まで冷却した。次いで、重合反応槽中に、硫酸第一鉄０．００３部、ホルムアルデヒドスルホキシル酸ナトリウム０．０２部、および、クメンハイドロパーオキサイド０．００８部を滴下し反応を開始させた。その後、５時間掛けて反応を行い、重合転化率が９０．５％となった時点で、重合停止剤としてのハイドロキノンを添加して重合反応を停止し、乳化重合液を得た。そして、実施例１と同様にして、凝固工程、洗浄工程、および乾燥工程を行うことで、固形状のカルボキシル基含有アクリルゴム（Ａ－９）を得て、同様に各測定を行った。結果を表１に示す。 [Comparative Example 4]
(Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-9))
In a polymerization reaction tank equipped with a thermometer and a stirrer, 200 parts of pure water, 45 parts of ethyl acrylate, 53.2 parts of n-butyl acrylate, 1.8 parts of mono-n-butyl fumarate, and anionic surfactant. Sodium lauryl sulfate (trade name "Emar 2FG", manufactured by Kao) as an activator, 1.5 parts, and polyoxyethylene dodecyl ether (trade name "Emargen 105", manufactured by Kao) as a nonionic surfactant 0 .3 parts, 0.01 part of ethylenediamine tetraacetic acid (EDTA) was charged, stirred, and cooled to a temperature of 15 ° C. under a nitrogen stream. Next, 0.003 parts of ferrous sulfate, 0.02 parts of sodium formaldehyde sulfoxylate, and 0.008 parts of cumene hydroperoxide were added dropwise to the polymerization reaction tank to initiate the reaction. Then, the reaction was carried out over 5 hours, and when the polymerization conversion rate reached 90.5%, hydroquinone as a polymerization terminator was added to stop the polymerization reaction to obtain an emulsion polymerization solution. Then, the solidification step, the washing step, and the drying step were carried out in the same manner as in Example 1 to obtain a solid carboxyl group-containing acrylic rubber (A-9), and each measurement was carried out in the same manner. The results are shown in Table 1.
（ゴム組成物の調製）
　上記にて得られたカルボキシル基含有アクリルゴム（Ａ－９）を用いた以外は、実施例１と同様にして、ゴム組成物を調製し、同様に各測定を行った。結果を表１に示す。 (Preparation of rubber composition)
A rubber composition was prepared in the same manner as in Example 1 except that the carboxyl group-containing acrylic rubber (A-9) obtained above was used, and each measurement was carried out in the same manner. The results are shown in Table 1.
［比較例５］
（カルボキシル基含有アクリルゴム（Ａ－１０）の製造）
　クメンハイドロパーオキサイドの使用量を０．０１部に変更したこと、反応時間を１２時間に変更し、重合転化率が９５．１％となるまで重合反応を行ったこと以外は、比較例４と同様にして、固形状のカルボキシル基含有アクリルゴム（Ａ－１０）を得て、同様に各測定を行った。結果を表１に示す。 [Comparative Example 5]
(Manufacturing of Carboxyl Group-Containing Acrylic Rubber (A-10))
Compared with Comparative Example 4, except that the amount of cumene hydroperoxide used was changed to 0.01 part, the reaction time was changed to 12 hours, and the polymerization reaction was carried out until the polymerization conversion was 95.1%. In the same manner, a solid carboxyl group-containing acrylic rubber (A-10) was obtained, and each measurement was carried out in the same manner. The results are shown in Table 1.
（ゴム組成物の調製）
　上記にて得られたカルボキシル基含有アクリルゴム（Ａ－１０）を用いた以外は、実施例１と同様にして、ゴム組成物を調製し、同様に各測定を行った。結果を表１に示す。 (Preparation of rubber composition)
A rubber composition was prepared in the same manner as in Example 1 except that the carboxyl group-containing acrylic rubber (A-10) obtained above was used, and each measurement was carried out in the same manner. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
 　なお、表１中において、比較例４，５は、一括で重合反応を行ったものであるが、各単量体や乳化剤、重合開始剤の使用量等については、単量体乳化液調製工程および初期重合工程の欄に記載した。
Figure JPOXMLDOC01-appb-T000001
 In Table 1, Comparative Examples 4 and 5 are the ones in which the polymerization reaction was carried out all at once, but the amount of each monomer, emulsifier, polymerization initiator used, etc. is the monomer emulsion preparation step. And described in the column of initial polymerization step.
　表１に示すように、カルボキシル基含有量が５．０×１０－３～１．５×１０－２ｍｅｐｈｒの範囲であり、エタノール水溶液抽出操作により抽出される、エタノール水溶液抽出量が３．０～８．０重量％であり、かつ、エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量が０．２×１０－３～１．２×１０－３ｍｅｐｈｒの範囲である場合には、カルボキシル基含有アクリルゴムは、加工性に優れたものであり、また、これのようなカルボキシル基含有アクリルゴムを用いて得られるゴム架橋物は、耐圧縮永久歪み性に優れるものであった（実施例１～５）。 As shown in Table 1, the carboxyl group content is in the range of 5.0 × 10 -3 to 1.5 × 10 −2 mephr, and the amount of ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation is 3.0. It is ~ 8.0% by weight, and the amount of change in the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is in the range of 0.2 × 10 -3 to 1.2 × 10 -3 mephr. In some cases, the carboxyl group-containing acrylic rubber is excellent in processability, and the rubber crosslinked product obtained by using the carboxyl group-containing acrylic rubber such as this is excellent in compression permanent strain resistance. (Examples 1 to 5).
　一方、エタノール水溶液抽出操作により抽出される、エタノール水溶液抽出量が少なすぎる場合には、カルボキシル基含有アクリルゴムは、加工性に劣るものとなり（比較例１，３～５）、特に、エタノール水溶液抽出量が０．７０重量％、１．１０重量％と非常に少ない比較例４，５においては、ゴム架橋物とした場合における耐圧縮永久歪み性にも劣るものであった。
　また、エタノール水溶液抽出操作により抽出される、エタノール水溶液抽出量が３．０～８．０重量％の範囲であっても、エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量が大きすぎる場合には、ゴム架橋物とした場合における耐圧縮永久歪み性にも劣るものとなる結果となった（比較例２）。 On the other hand, when the amount of the ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation is too small, the carboxyl group-containing acrylic rubber is inferior in processability (Comparative Examples 1, 3 to 5), and in particular, the ethanol aqueous solution is extracted. In Comparative Examples 4 and 5, in which the amounts were very small, 0.70% by weight and 1.10% by weight, the compressive permanent strain resistance in the case of a rubber crosslinked product was also inferior.
Further, even if the extraction amount of the ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation is in the range of 3.0 to 8.0% by weight, the change in the carboxyl group content when the extraction is performed by the ethanol aqueous solution extraction operation. If the amount is too large, the result is that the compression set resistance in the case of a rubber crosslinked product is also inferior (Comparative Example 2).

Claims (7)

  1. 　（メタ）アクリル酸エステル単量体単位およびカルボキシル基含有単量体単位を含有するカルボキシル基含有アクリルゴムであって、
    　カルボキシル基含有量が、前記カルボキシル基含有アクリルゴム１００ｇ当たりのカルボキシル基のモル数で、５．０×１０－３～１．５×１０－２ｍｅｐｈｒの範囲であり、
    　エタノールを７５体積％および水を２５体積％の割合で含有するエタノール水溶液を用いたエタノール水溶液抽出操作により抽出される、エタノール水溶液抽出量が３．０～８．０重量％であり、
    　前記エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量が０．２×１０－３～１．２×１０－３ｍｅｐｈｒの範囲である、カルボキシル基含有アクリルゴム。     A carboxyl group-containing acrylic rubber containing a (meth) acrylic acid ester monomer unit and a carboxyl group-containing monomer unit.
    The carboxyl group content is the number of moles of carboxyl groups per 100 g of the carboxyl group-containing acrylic rubber, and is in the range of 5.0 × 10 -3 to 1.5 × 10 −2 mephr.
    The amount of the ethanol aqueous solution extracted by the ethanol aqueous solution extraction operation using the ethanol aqueous solution containing 75% by volume of ethanol and 25% by volume of water is 3.0 to 8.0% by weight.
    A carboxyl group-containing acrylic rubber having a change in the carboxyl group content in the range of 0.2 × 10 -3 to 1.2 × 10 -3 mephr when extracted by the ethanol aqueous solution extraction operation.
  2. 　前記カルボキシル基含有単量体単位が、ブテンジオン酸モノエステル単量体単位である請求項１に記載のカルボキシル基含有アクリルゴム。 The carboxyl group-containing acrylic rubber according to claim 1, wherein the carboxyl group-containing monomer unit is a butendionic acid monoester monomer unit.
  3. 　前記カルボキシル基含有単量体単位が、フマル酸モノエステル単量体単位である請求項２に記載のカルボキシル基含有アクリルゴム。 The carboxyl group-containing acrylic rubber according to claim 2, wherein the carboxyl group-containing monomer unit is a fumaric acid monoester monomer unit.
  4. 　前記エタノール水溶液抽出量が４．０～６．５重量％である請求項１～３のいずれかに記載のカルボキシル基含有アクリルゴム。 The carboxyl group-containing acrylic rubber according to any one of claims 1 to 3, wherein the extraction amount of the aqueous ethanol solution is 4.0 to 6.5% by weight.
  5. 　前記エタノール水溶液抽出操作により抽出を行った際における、カルボキシル基含有量の変化量が０．５×１０－３～０．８×１０－３ｍｅｐｈｒの範囲である請求項１～４のいずれかに記載のカルボキシル基含有アクリルゴム。 Any one of claims 1 to 4 in which the amount of change in the carboxyl group content when extraction is performed by the ethanol aqueous solution extraction operation is in the range of 0.5 × 10 -3 to 0.8 × 10 -3 mephr. The above-mentioned carboxyl group-containing acrylic rubber.
  6. 　請求項１～５のいずれかに記載のカルボキシル基含有アクリルゴムを含むゴム成分と、架橋剤とを含有するゴム組成物。 A rubber composition containing a rubber component containing the carboxyl group-containing acrylic rubber according to any one of claims 1 to 5 and a cross-linking agent.
  7. 　請求項６に記載のゴム組成物を架橋してなるゴム架橋物。 A rubber crosslinked product obtained by cross-linking the rubber composition according to claim 6.
PCT/JP2021/042818 2020-11-30 2021-11-22 Carboxyl group-containing acrylic rubber, rubber composition, and rubber crosslink product WO2022113937A1 (en)

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