Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
• • 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
  • C08F263/00—Macromolecular compounds obtained by polymerising monomers on to polymers of esters of unsaturated alcohols with saturated acids as defined in group C08F18/00
  • C08F263/02—Macromolecular compounds obtained by polymerising monomers on to polymers of esters of unsaturated alcohols with saturated acids as defined in group C08F18/00 on to polymers of vinyl esters with monocarboxylic acids
  • C08F263/04—Macromolecular compounds obtained by polymerising monomers on to polymers of esters of unsaturated alcohols with saturated acids as defined in group C08F18/00 on to polymers of vinyl esters with monocarboxylic acids on to polymers of vinyl acetate
• • 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
  • C08F8/00—Chemical modification by after-treatment
• • 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
  • C08L33/08—Homopolymers or copolymers of acrylic acid esters
• • 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
  • C08F218/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid
  • C08F218/02—Esters of monocarboxylic acids
  • C08F218/04—Vinyl esters
  • C08F218/08—Vinyl acetate
• • 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
  • C08F2800/00—Copolymer characterised by the proportions of the comonomers expressed
  • C08F2800/20—Copolymer characterised by the proportions of the comonomers expressed as weight or mass percentages
• • 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
  • C08F2810/00—Chemical modification of a polymer
  • C08F2810/20—Chemical modification of a polymer leading to a crosslinking, either explicitly or inherently
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2331/00—Characterised by the use of copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, or carbonic acid, or of a haloformic acid
  • C08J2331/02—Characterised by the use of omopolymers or copolymers of esters of monocarboxylic acids
  • C08J2331/04—Homopolymers or copolymers of vinyl acetate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2333/00—Characterised by the use 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; Derivatives of such polymers
  • C08J2333/04—Characterised by the use 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; Derivatives of such polymers esters
  • C08J2333/06—Characterised by the use 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; Derivatives of such polymers esters of esters containing only carbon, hydrogen, and oxygen, the oxygen atom being present only as part of the carboxyl radical
  • C08J2333/08—Homopolymers or copolymers of acrylic acid esters
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/14—Peroxides

Definitions

• This disclosure relates to acrylic rubber, a rubber composition, and a crosslinked product thereof.
• Patent Document 1 discloses an acrylic rubber composition obtained by copolymerizing 100 parts by mass of (meth)acrylic acid alkyl ester, 1 to 10 parts by mass of vinyl acetate, and 1 to 3 parts by mass of cross-linking monomer, as an acrylic rubber composition that does not impair normal physical properties and has excellent heat resistance, particularly elongation at break and residual elongation after thermal aging.
• the inventors' research has revealed that attempts to increase the tensile strength, which is one of the mechanical properties (normal physical properties) of cross-linked acrylic rubber, can sometimes result in a deterioration in the oil resistance of the cross-linked product.
• one aspect of the present invention aims to provide an acrylic rubber that produces a cross-linked product with high tensile strength and excellent oil resistance.
• the inventors have discovered that, in an acrylic rubber containing (meth)acrylic acid ester, carboxylic acid vinyl ester, and ethylene as monomer units, when the carboxylic acid vinyl ester content and the ethylene content are each equal to or greater than a predetermined amount, it is possible to provide an acrylic rubber that provides a crosslinked product with high tensile strength and excellent oil resistance.
• the present invention includes the following aspects.
• An acrylic rubber containing a (meth)acrylic acid ester, a carboxylate vinyl ester, and ethylene as monomer units, the content of the carboxylate vinyl ester being 15 mass% or more and the content of ethylene being 5 mass% or more based on the total amount of the monomer units in the acrylic rubber.
• [4] The acrylic rubber according to any one of [1] to [3], wherein the carboxylic acid vinyl ester includes at least one selected from the group consisting of vinyl acetate, vinyl neodecanoate, and vinyl laurate.
• [5] A rubber composition comprising the acrylic rubber according to any one of [1] to [4] and a crosslinking agent.
• [6] A crosslinked product of the rubber composition according to [5].
• One aspect of the present invention is to provide an acrylic rubber that can produce a cross-linked product with high tensile strength and excellent oil resistance.
• One embodiment of the present invention is an acrylic rubber that contains (meth)acrylic acid esters, vinyl carboxylates, and ethylene as monomer units.
• (meth)acrylic acid esters is used to include both acrylic acid esters and the corresponding methacrylic acid esters.
• the (meth)acrylic acid ester preferably includes at least one selected from the group consisting of (meth)acrylic acid alkyl esters and (meth)acrylic acid alkoxy esters.
• the alkyl group in the (meth)acrylic acid alkyl ester may be linear or branched.
• the number of carbon atoms in the alkyl group in the (meth)acrylic acid alkyl ester may be 1 or more and 16 or less.
• the content of (meth)acrylic acid alkyl ester may be 10 mass% or more, 20 mass% or more, 30 mass% or more, 40 mass% or more, or 50 mass% or more based on the total amount of monomer units in the acrylic rubber, and may be 90 mass% or less, 80 mass% or less, 70 mass% or less, or 60 mass% or less.
• the (meth)acrylic acid alkyl ester includes at least one selected from the group consisting of acrylic acid esters and methacrylic acid esters, and preferably includes an acrylic acid ester.
• the alkyl acrylate is represented by the following formula (1).
• R 1 represents an alkyl group.
• the alkyl group (R 1 ) in the alkyl acrylate ester may be linear or branched.
• the number of carbon atoms in the alkyl group (R 1 ) in the alkyl acrylate ester may be 1 or more and 16 or less.
• alkyl acrylate ester examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-methylpentyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, hexadecyl acrylate, 1-adamantyl acrylate, and cyclohexyl acrylate.
• These alkyl acrylate esters may be used alone or in combination of two or more.
• the content of the acrylic acid alkyl ester may be 10 mass% or more, 20 mass% or more, 30 mass% or more, 40 mass% or more, or 50 mass% or more, and may be 90 mass% or less, 80 mass% or less, 70 mass% or less, or 60 mass% or less, based on the total amount of monomer units in the acrylic rubber.
• the alkyl acrylate preferably includes an alkyl acrylate (first alkyl acrylate) having an alkyl group having 3 or less carbon atoms ( R1 is an alkyl group having 3 or less carbon atoms).
• the alkyl acrylate may further include an alkyl acrylate (second alkyl acrylate) having an alkyl group having 4 or more carbon atoms ( R1 is an alkyl group having 4 or more carbon atoms).
• the number of carbon atoms in the alkyl group in the first alkyl acrylate may be 1 or more, 2 or less, or even 2.
• the first alkyl acrylate is preferably ethyl acrylate.
• the number of carbon atoms in the alkyl group in the second alkyl acrylate may be 8 or less, 6 or less, or 5 or less, or even 4.
• the second alkyl acrylate is preferably n-butyl acrylate.
• the content of the first acrylic acid alkyl ester may be 10 mass% or more, 20 mass% or more, 30 mass% or more, 40 mass% or more, or 50 mass% or more based on the total amount of monomer units in the acrylic rubber, and may be 90 mass% or less, 80 mass% or less, 70 mass% or less, or 60 mass% or less.
• the content of the second alkyl acrylate may be 5% by mass or more, 10% by mass or more, or 20% by mass or more, and may be 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total amount of monomer units in the acrylic rubber.
• the alkyl methacrylate ester is represented by the following formula (2).
• R2 represents an alkyl group.
• the alkyl group (R 2 ) in the methacrylic acid alkyl ester may be linear or branched.
• the number of carbon atoms in the alkyl group (R 2 ) in the methacrylic acid alkyl ester may be 1 or more, or 4 or less, preferably 2 or more or 3 or more, and may be 3.
• Specific examples of the methacrylic acid alkyl ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and the like. These methacrylic acid alkyl esters may be used alone or in combination of two or more.
• the methacrylic acid alkyl ester is preferably n-butyl methacrylate from the viewpoint of improving the heat resistance of the acrylic rubber.
• the content of the methacrylic acid alkyl ester may be 5% by mass or more, 7% by mass or more, or 10% by mass or more, and may be 30% by mass or less, 20% by mass or less, or 15% by mass or less, based on the total amount of monomer units in the acrylic rubber.
• the alkoxyalkyl (meth)acrylate is represented by the following formula (3).
• R 3 represents a hydrogen atom or a methyl group
• R 4 represents an alkylene group
• R 5 represents an alkyl group.
• the alkylene group (R 4 ) and the alkyl group (R 5 ) in the (meth)acrylic acid alkoxyalkyl ester may each be linear or branched.
• the number of carbon atoms in the alkylene group (R 4 ) in the (meth)acrylic acid alkoxyalkyl ester may be 1 or more or 2 or more, and 4 or less or 3 or less.
• the number of carbon atoms in the alkyl group (R 5 ) in the (meth)acrylic acid alkoxyalkyl ester may be 1 or more, and 4 or less, 3 or less, or 2 or less.
• (meth)acrylic acid alkoxyalkyl esters include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(n-propoxy)ethyl (meth)acrylate, 2-(n-butoxy)ethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 2-(n-propoxy)propyl (meth)acrylate, and 2-(n-butoxy)propyl acrylate.
• These (meth)acrylic acid alkoxyalkyl esters may be used alone or in combination of two or more.
• the content of (meth)acrylic acid alkoxyalkyl ester may be 5 mass% or more, 10 mass% or more, or 15 mass% or more based on the total amount of monomer units in the acrylic rubber, and may be 30 mass% or less, 25 mass% or less, or 20 mass% or less.
• the vinyl carboxylate is preferably a vinyl carboxylate (vinyl ester of an aliphatic monocarboxylic acid) represented by the following formula (4).
• R6 represents an alkyl group.
• the alkyl group represented by R6 may be linear or branched.
• the number of carbon atoms in the alkyl group represented by R6 may be 1 or more, and may be 12 or less, 11 or less, 10 or less, or 9 or less.
• Specific examples of the vinyl carboxylate include vinyl acetate, vinyl neodecanoate, vinyl laurate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl octylate, and vinyl pivalate.
• the vinyl carboxylate preferably includes at least one selected from the group consisting of vinyl acetate, vinyl neodecanoate, and vinyl laurate, and more preferably includes vinyl acetate.
• the content of the carboxylic acid vinyl ester is 15% by mass or more, based on the total amount of monomer units in the acrylic rubber, from the viewpoint of obtaining a crosslinked product having high tensile strength and excellent oil resistance, and from the viewpoint of making the crosslinked product easier to obtain, it may be preferably 17% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, or 35% by mass or more, or 80% by mass or less, 75% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less.
• the ethylene content is 5% by mass or more, based on the total amount of monomer units in the acrylic rubber, from the viewpoint of obtaining a crosslinked product having high tensile strength and excellent oil resistance, and from the viewpoint of making the crosslinked product easier to obtain, it may be preferably 6% by mass or more, 7% by mass or more, 8% by mass or more, 9% by mass or more, or 10% by mass or more, and may be 20% by mass or less, 17% by mass or less, or 15% by mass or less.
• the mass ratio of the ethylene content to the vinyl carboxylate content is preferably 0.1 to 0.5, from the viewpoint of making it easier to obtain a crosslinked product having high tensile strength and excellent oil resistance.
• the lower limit of the mass ratio may be 0.12, 0.14, 0.16, or 0.18.
• the upper limit of the mass ratio may be 0.4, 0.3, 0.25, 0.23, or 0.21.
• the acrylic rubber may further contain a crosslinking monomer as a monomer unit.
• the crosslinking monomer is a monomer that is copolymerizable with (meth)acrylic acid esters, vinyl carboxylates, and ethylene and has a crosslinkable group that forms a crosslinking site (also called a crosslinking point).
• the crosslinking monomer has a polymerizable carbon-carbon double bond, and has, for example, an acryloyl group, a methacryloyl group, an allyl group, a methallyl group, a vinyl group, or an alkenylene group.
• Examples of the crosslinking group include a carboxyl group, an epoxy group, and an active chlorine group.
• the crosslinking monomer may have one or more of these crosslinking groups.
• a monomer that can be either one of a (meth)acrylic acid ester and a vinyl carboxylate, and can also be a crosslinking monomer is classified as a crosslinking monomer.
• crosslinkable monomers having a carboxyl group as a crosslinkable group include acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, itaconic acid, and maleic acid monoalkyl esters.
• cross-linking monomers having an epoxy group as a cross-linking group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and methallyl glycidyl ether.
• crosslinkable monomers having an active chlorine group as a crosslinkable group examples include 2-chloroethyl vinyl ether, 2-chloroethyl acrylate, vinylbenzyl chloride, vinyl chloroacetate, and allyl chloroacetate.
• the content of the crosslinking monomer may be 0.5% by mass or more, 1% by mass or more, or 1.5% by mass or more, and may be 10% by mass or less, 7% by mass or less, or 4% by mass or less, based on the total amount of monomer units in the acrylic rubber.
• the acrylic rubber may contain, as a monomer unit, other monomers that are copolymerizable with the above-mentioned monomers.
• other monomers include alkyl vinyl ketones, vinyl ethers, allyl ethers, vinyl aromatic compounds, vinyl nitriles, maleic acid dialkyl esters, fumaric acid dialkyl esters, itaconic acid dialkyl esters, citraconic acid dialkyl esters, mesaconic acid dialkyl esters, 2-pentenedioic acid dialkyl esters, and acetylenedicarboxylic acid dialkyl esters.
• Acrylic rubber can be obtained by copolymerizing the above monomers using known polymerization methods such as emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization, preferably suspension polymerization.
• a monomer mixture containing all of the monomers constituting the acrylic rubber may be prepared, and ethylene may be injected into the monomer mixture to initiate polymerization.
• ethylene may be injected into the monomer mixture to initiate polymerization.
• a monomer mixture containing a part of the carboxylic acid vinyl ester to be used is prepared, while the remainder of the carboxylic acid vinyl ester to be used or a solution thereof, and all of the (meth)acrylic acid ester to be used or a solution thereof are separately prepared.
• ethylene is injected into the monomer mixture to initiate polymerization, and simultaneously with the start of polymerization, the remainder of the carboxylic acid vinyl ester or a solution thereof, and all of the (meth)acrylic acid ester or a solution thereof are added to the system at a constant rate until the polymerization is completed.
• the mass ratio (part of the carboxylic acid vinyl ester: remainder of the carboxylic acid vinyl ester) of the part of the carboxylic acid vinyl ester to be used in the monomer mixture and the remainder of the carboxylic acid vinyl ester is preferably 10:90 to 70:30, more preferably 20:80 to 60:40.
• Another embodiment of the present invention is a rubber composition containing the above-mentioned acrylic rubber.
• the rubber composition may further contain a crosslinking agent.
• the rubber composition may further contain a crosslinking accelerator.
• a crosslinked product can be obtained by kneading the rubber composition at a temperature below the crosslinking temperature and then heating it at a predetermined crosslinking temperature.
• Another embodiment of the present invention is a crosslinked product of the above-mentioned rubber composition.
• the heating conditions for crosslinking can be set appropriately depending on the composition of the rubber composition and the type of crosslinking agent.
• the heating temperature may be 100°C or higher and 200°C or lower.
• the heating time may be 1 hour or higher and 10 hours or lower.
• a method used for crosslinking rubber such as hot press heating, steam heating, or oven heating, can be used.
• the equipment used for kneading, molding, and crosslinking the rubber composition can be equipment that is normally used for rubber compositions.
• kneading equipment rolls, kneaders, Banbury mixers, internal mixers, twin-screw extruders, etc. can be used.
• crosslinking agent is not particularly limited as long as it is one that is normally used for crosslinking acrylic rubber.
• crosslinking agents include amine compounds, imidazole compounds, organic peroxides, and polyfunctional (meth)acrylic acid ester compounds having two or more (meth)acryloyl groups.
• the content of the crosslinking agent in the rubber composition may be 0.1 parts by mass or more, 0.5 parts by mass or more, or 1 part by mass or more, and may be 15 parts by mass or less, 10 parts by mass or less, or 5 parts by mass or less, per 100 parts by mass of the acrylic rubber.
• the crosslinking accelerator is not particularly limited as long as it is one that is commonly used for crosslinking acrylic rubber.
• crosslinking accelerators include thiazine compounds, quaternary onium salts, guanidine compounds, tertiary phosphine compounds, alkali metal salts of weak acids, and diazabicycloalkene compounds.
• the content of the crosslinking accelerator may be 0.1 parts by mass or more, 0.2 parts by mass or more, or 0.3 parts by mass or more, and 5 parts by mass or less, 4 parts by mass or less, or 3 parts by mass or less, per 100 parts by mass of the acrylic rubber.
• the rubber composition may further contain a filler (reinforcing agent).
• a filler forcing agent
• examples of fillers include carbon black, silica, talc, and calcium carbonate.
• the amount of the filler may be, for example, 30 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the acrylic rubber.
• the rubber composition may further contain a lubricant.
• lubricants include liquid paraffin, stearic acid, stearylamine, zinc fatty acid, fatty acid ester, and organosilicone.
• the amount of the lubricant contained may be, for example, 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the acrylic rubber.
• the rubber composition may further contain an anti-aging agent.
• the anti-aging agent include amine-based anti-aging agents and phenol-based anti-aging agents.
• the content of the anti-aging agent may be, for example, 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the acrylic rubber.
• the rubber composition may further contain a surfactant.
• the surfactant include alkyl sulfate ester salts.
• the content of the surfactant may be, for example, 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the acrylic rubber.
• the rubber composition may further contain a release agent.
• the release agent include phosphate esters.
• the content of the release agent may be, for example, 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the acrylic rubber.
• the rubber composition described above is preferably used as a rubber composition for seals (also called sealing members) or hoses (also called hose members).
• the rubber composition can also be used as a rubber composition for anti-vibration rubber (also called anti-vibration rubber members) or wire-coated rubber (also called wire-coated rubber members).
• the cross-linked product of the rubber composition described above is preferably used as a seal or hose. That is, another embodiment of the present invention is a seal or hose containing the above-mentioned cross-linked product.
• the cross-linked product can also be used as anti-vibration rubber or wire-coated rubber. That is, another embodiment of the present invention is an anti-vibration rubber containing the above-mentioned cross-linked product.
• hoses examples include rubber hoses, etc.
• seals examples include gaskets, packings, etc. These components may consist of only the cross-linked product of the rubber composition, or may include the cross-linked product and other parts.
• hoses include transmission oil cooler hoses for automobiles, construction machinery, hydraulic equipment, etc., engine oil cooler hoses, air duct hoses, turbo intercooler hoses, hot air hoses, radiator hoses, power steering hoses, fuel system hoses, drain system hoses, etc.
• the hose components may have reinforcing yarn or wire in the middle layer or outermost layer of the hose.
• seals include engine head cover gaskets, oil pan gaskets, oil seals, lip seal packings, O-rings, transmission seal gaskets, crankshafts, camshaft seal gaskets, valve stems, power steering seals, belt cover seals, constant velocity joint boot materials, and rack and pinion boot materials.
• anti-vibration rubber examples include damper pulleys, center support cushions, and suspension bushings.
• Example 1 Manufacture of acrylic rubber
• 5 kg of vinyl acetate, 12 kg of a 5% by mass aqueous solution of partially saponified polyvinyl alcohol (saponification degree of polyvinyl alcohol: 88 mol%), and 31 g of sodium acetate were charged into a pressure-resistant reaction vessel with an internal volume of 40 liters, and mixed thoroughly in advance with a stirrer to prepare a uniform suspension.
• 5 kg of vinyl acetate and 3 kg of an alkyl acrylate (ethyl acrylate, butyl acrylate) were separately prepared. After the air in the upper part of the vessel was replaced with nitrogen, ethylene was forced into the upper part of the vessel at a pressure of 5 MPa.
• the monomer composition of the obtained acrylic rubber was measured by 1 H-NMR (AVANCE III HD500, manufactured by Bruker) for a solution in which the acrylic rubber was dissolved in chloroform.
• Nocrac CD 0.5 parts by mass of a release agent (fatty acid, fatty acid ester, amine, wetting agent mixture, Axel Corporation "Mold With INT-21G"), 8 parts by mass of a crosslinking agent A (NOF Corporation "Perbutyl P-40"), 3 parts by mass of a crosslinking agent B (trimethylolpropane trimethacrylate, DIC Corporation "Monocizer TD-1500”), and 0.5 parts by mass of a crosslinking accelerator A (phenothiazine, Seiko Chemical Co., Ltd.) were kneaded with an 8-inch open roll to obtain a rubber composition.
• a release agent fatty acid, fatty acid ester, amine, wetting agent mixture, Axel Corporation "Mold With INT-21G
• a crosslinking agent A NOF Corporation "Perbutyl P-40
• 3 parts by mass of a crosslinking agent B trimethylolpropane trimethacrylate, DIC Corporation "Monocizer
• the obtained rubber composition was cut into a sheet having a thickness of 2.4 mm, and then heated and pressed at 170°C and a pressure of 4 MPa for 20 minutes using a press vulcanizer to obtain a primary crosslinked product of the rubber composition. Subsequently, the primary crosslinked product was heated in a gear oven at 170°C for 4 hours to obtain a secondary crosslinked product of the rubber composition.
• the tensile strength of the obtained secondary crosslinked product was measured in accordance with JIS K6251:2010.
• Example 2 to 4 Acrylic rubber was produced, a rubber composition was prepared, and a crosslinked product was produced in the same manner as in Example 1, except that the monomer composition was changed as shown in Table 1.
• the monomer composition of the obtained acrylic rubber was calculated in the same manner as in Example 1.
• the tensile strength of the obtained secondary crosslinked product was measured in the same manner as in Example 1.
• the oil resistance of the obtained primary crosslinked product was evaluated in the same manner as in Example 1.
• Example 5 An acrylic rubber was produced in the same manner as in Example 1, except that the monomer composition was changed as shown in Table 1. The monomer composition was calculated in the same manner as in Example 1. Next, 100 parts by mass of the obtained acrylic rubber, 50 parts by mass of a filler (carbon black, manufactured by Tokai Carbon Co., Ltd., "Seat SO"), 1 part by mass of a lubricant A (stearic acid, manufactured by Kao Corporation, “Lunac S-90”), 0.5 parts by mass of an amine-based antiaging agent (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocrac CD”), 0.5 parts by mass of a release agent (a mixture of fatty acid, fatty acid ester, amine, and wetting agent, manufactured by Axel, "Mold With INT-21G”), 1.7 parts by mass of a crosslinking agent C (1-(2-cyanoethyl)-2-methylimidazole, manufactured by Shikoku Chemical Industry Co., Ltd., “
• a commercially available acrylic rubber (“VAMAC DP” manufactured by Du Pont) was used as the acrylic rubber.
• This acrylic rubber contains an alkyl acrylate and ethylene, but does not contain a vinyl carboxylate.
• a filler carbon black, manufactured by Tokai Carbon Co., Ltd., "Seat SO”
• a lubricant A stearic acid, manufactured by Kao Corporation, "Lunac S-90”
• an amine-based anti-aging agent manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocrac CD”
• a release agent a mixture of fatty acid, fatty acid ester, amine, and wetting agent, manufactured by Axel, "Mold With INT-21G
• a lubricant B stearylamine, manufactured by Kao Corporation, "Farmin 80S
• a cross-linked product was produced using the obtained rubber composition in the same manner as in Example 1.
• the tensile strength of the obtained secondary cross-linked product was measured in the same manner as in Example 1.
• the oil resistance of the obtained primary cross-linked product was evaluated in the same manner as in Example 1.
• Table 1 shows the monomer composition of each acrylic rubber used in the examples and comparative examples, as well as the tensile strength measurement results and oil resistance evaluation results for each example and comparative example.
• the acrylic rubbers of Examples 1 to 5 produced cross-linked products with high tensile strength and excellent oil resistance.
• the acrylic rubber of Comparative Example 1 produced a cross-linked product with relatively high tensile strength, but the oil resistance of the cross-linked product was significantly poor.
• the acrylic rubbers of Comparative Examples 2 to 3 produced cross-linked products with low tensile strength.

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