JP5163390B2 - Acrylic rubber - Google Patents

Description

  The present invention relates to an acrylic rubber, and more particularly to an acrylic rubber that is excellent in processability such as roll processability and can provide a crosslinked product excellent in normal properties and cold resistance.

  Acrylic rubber is excellent in heat resistance, oil resistance, and the like, and is therefore widely used as a material for rubber parts such as seals, hoses, vibration-proofing materials, tubes, and belts in fields related to automobiles. Acrylic rubber is crosslinked so that it can be used as these parts and imparts rubber elasticity. For this purpose, a crosslinkable monomer having an active crosslinking point is usually copolymerized in an amount of about 1 to 5% by weight. As the crosslinkable monomer, chlorine monomers such as 2-chloroethyl vinyl ether and vinyl chloroacetate, and epoxy monomers such as allyl glycidyl ether are generally used.

  In addition, as crosslinkable monomers, those other than those described above have been studied. For example, Patent Document 1 discloses an acrylic rubber using a butenedionic acid monoester having an alicyclic structure such as monocyclohexyl fumarate. . In Patent Document 1, by using butenedionic acid monoester as a crosslinkable monomer, the scorch stability of acrylic rubber is improved, thereby improving the heat resistance and compression set in the case of a crosslinked product. .

  On the other hand, in addition to heat resistance and oil resistance, rubber parts used in fields related to automobiles are required to have cold resistance. However, the acrylic rubber described in Patent Document 1 has insufficient cold resistance, and therefore an acrylic rubber having excellent cold resistance has been desired.

JP 2004-18567 A

  An object of the present invention is to provide an acrylic rubber which is excellent in processability such as roll processability and can give a crosslinked product excellent in normal properties and cold resistance. Another object of the present invention is to provide a crosslinkable rubber composition obtained by adding a crosslinking agent to such an acrylic rubber, and a rubber cross-linked product obtained by crosslinking the crosslinkable rubber composition.

  As a result of diligent research to solve the above problems, the present inventors have found that a (meth) acrylic acid ester monomer unit (A) having an alkyl group or alkoxyalkyl group having a small number of carbon atoms, an alkyl group having a large number of carbon atoms or The above object can be achieved with an acrylic rubber containing a (meth) acrylic acid ester monomer unit (B) having an alkoxyalkyl group and a di (meth) acrylic acid ester monomer unit (C) in a predetermined ratio. As a result, the present invention has been completed.

（Ｒ_１は、水素原子またはメチル基、Ｘは、炭素数１〜３のアルキル基または炭素数２〜３のアルコキシアルキル基） That is, according to the present invention , a (meth) acrylic acid ester monomer unit (A1) represented by the following formula (1), wherein X is an alkyl group having 1 to 3 carbon atoms in the following formula (1): 1 to 20% by weight, represented by the following formula (1), and in the following formula (1), (meth) acrylic acid ester monomer unit (A2) 1 in which X is an alkoxyalkyl group having 2 to 3 carbon atoms ˜39 wt% , (meth) acrylic acid ester monomer unit (B) having 5 to 89.8 wt% of alkyl group having 4 to 8 carbon atoms or alkoxyalkyl group having 4 to 8 carbon atoms, and di (meth) ) have a 0.1-5% by weight of acrylic acid ester monomer units (C), in the monomer units (A1) and the monomer units (A2) the total content ratio of 10 to 40 wt% of An acrylic rubber is provided.

_{(R 1} is a hydrogen atom or a methyl group, X is an alkoxy shear alkyl group of the alkyl group carbon atoms or 2 to 3 1 to 3 carbon atoms)

  The acrylic rubber of the present invention preferably has a butenedionic acid monoester monomer unit (D) having an alicyclic structure, and a content ratio of the butenedionic acid monoester monomer unit (D) having the alicyclic structure. Is 0.1 to 20% by weight.

  Moreover, according to this invention, the crosslinkable rubber composition formed by containing the said acrylic rubber and a crosslinking agent is provided.

  Furthermore, according to this invention, the rubber crosslinked material formed by bridge | crosslinking the said crosslinkable rubber composition is provided.

  According to the present invention, an acrylic rubber and a crosslinkable rubber composition that are excellent in processability such as roll processability, and can give a crosslinked product excellent in normal physical properties and cold resistance, and obtained by crosslinking this, A rubber cross-linked product excellent in physical properties and cold resistance can be provided.

（Ｒ_１は、水素原子またはメチル基、Ｘは、炭素数１〜３のアルキル基または炭素数２〜３のアルコキシアルキル基） The acrylic rubber of the present invention is a (meth) acrylic acid ester monomer unit (A) represented by the following formula (1): 10 to 40% by weight, an alkyl group having 4 to 8 carbon atoms, or an alkyl group having 4 to 8 carbon atoms. (Meth) acrylic acid ester monomer unit (B) having 55 to 89.8% by weight having an alkoxyalkyl group, and di (meth) acrylic acid ester monomer unit (C) having 0.1 to 5% by weight It is rubber.

_{(R 1} is a hydrogen atom or a methyl group, X is an alkoxy shear alkyl group of the alkyl group carbon atoms or 2 to 3 1 to 3 carbon atoms)

As the (meth) acrylic acid ester monomer unit (A) represented by the formula (1) constituting the acrylic rubber of the present invention (hereinafter referred to as “monomer unit (A)” as appropriate), (Meth) acrylic acid ester monomer unit (A1) (hereinafter referred to as “monomer unit (A1)” as appropriate), wherein X in formula (1) is a C 1-3 alkyl group, or X in formula (1) is an alkoxy shear alkyl group having 2 to 3 carbon atoms (meth) acrylic acid ester monomer units (A2) (hereinafter, appropriately referred to as "monomer units (A2)".) However, in the present invention, those containing both the monomer unit (A1) and the monomer unit (A2) are preferred.

(Meth) acrylic acid having an alkyl group having 1 to 3 carbon atoms that forms a (meth) acrylic acid ester monomer unit (A1) in which X in the formula (1) is an alkyl group having 1 to 3 carbon atoms Examples of the ester monomer (a1) (hereinafter referred to as “monomer (a1)” as appropriate) include, for example, methyl (meth) acrylate (meaning methyl acrylate and methyl methacrylate. “(Meth)” is used in the same meaning.), Ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and the like. Also good. Of these, ethyl acrylate is preferred.
X in Formula (1) forms a an alkoxy shear alkyl group having 2 to 3 carbon atoms (meth) acrylic acid ester monomer units (A2), having a 2-3 alkoxyalkyl group having a carbon number (meth ) Acrylic acid ester monomer (a2) (hereinafter referred to as “monomer (a2)” as appropriate) includes methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, and (meth) acrylic acid. Examples thereof include ethoxymethyl, and these may be used in combination. Of these, methoxyethyl acrylate is preferred.

The content ratio of the monomer unit (A) in the acrylic rubber is 10 to 40% by weight, preferably 15 to 40% by weight, and more preferably 20 to 38% by weight in all the monomer units. . If the content ratio of the monomer unit (A) is too low, the tackiness of acrylic rubber, particularly the tackiness when a crosslinkable rubber composition is obtained, is increased, and roll processability may be lowered. On the other hand, when too high, cold resistance may deteriorate.
When the monomer unit (A) includes both the monomer unit (A1) and the monomer unit (A2), the content ratio of these monomer units (A1) is 1 -20% by weight, preferably 2-10% by weight, and the monomer unit (A2) is 1-39% by weight, preferably 5-38% by weight (provided that the monomer unit (A1) and the monomer unit ( A range of 10 to 40% by weight in total with A2) is preferred.

  A (meth) acrylic acid ester monomer unit (B) having an alkyl group having 4 to 8 carbon atoms or an alkoxyalkyl group having 4 to 8 carbon atoms (hereinafter referred to as “monomer unit (B)” as appropriate). A (meth) acrylic acid ester monomer (b) having a C 4-8 alkyl group or a C 4-8 alkoxyalkyl group (hereinafter referred to as “monomer (b)” as appropriate) .) Is, for example, an alkyl group having 4 to 8 carbon atoms such as n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. (Meth) acrylic acid ester monomers having: ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, methoxy (meth) acrylate Propyl, (meth) having an alkoxy alkyl group having 4 to 8 carbon atoms such as acrylic acid methoxybutyl (meth) acrylate monomer; and the like. These may use multiple types together. Among these, n-butyl acrylate is preferable.

  The content ratio of the monomer unit (B) in the acrylic rubber is 55 to 89.8% by weight, preferably 55 to 84.4% by weight, more preferably 56 to 78% in all the monomer units. .8% by weight. If the content ratio of the monomer unit (B) is too low, the cold resistance of the resulting crosslinked product may be lowered. On the other hand, when too high, roll workability may deteriorate.

  Di (meth) acrylic acid ester monomer unit (C) (hereinafter referred to as “monomer unit (C)” as appropriate) (hereinafter referred to as “monomer unit (C)”) The “monomer (c)” is appropriately selected as long as it is a compound having two (meth) acrylic acid ester structures in the molecule, but ethylene glycol di (meth) acrylate, 1, Diols such as 3-propanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,3-butylenediol di (meth) acrylate, and 1,6-hexanediol di (meth) acrylate; Diester with (meth) acrylic acid; polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, ethylene oxide and propylene And the like; such as a copolymer of di (meth) acrylate and propylene oxide, the diester of polyether and (meth) acrylic acid containing a hydroxyl group 2 or more. Among these, ethylene glycol di (meth) acrylate and a diester of (meth) acrylic acid with a polyether containing two or more hydroxyl groups are preferable. GPC using ethylene glycol di (meth) acrylate and standard polystyrene is preferable. More preferred is a diester of (meth) acrylic acid having a weight average molecular weight of 200 to 1,000 and containing two or more hydroxyl groups, and containing two or more hydroxyl groups having a weight average molecular weight of 300 to 500 More preferred are diesters of polyether and (meth) acrylic acid. In addition, as a diester of the said polyether and (meth) acrylic acid, polyethyleneglycol di (meth) acrylate is preferable. The monomer (c) acts as an internal crosslinkable monomer that generates a crosslinked structure during polymerization.

  The content ratio of the monomer unit (C) in the acrylic rubber is 0.1 to 5% by weight, preferably 0.1 to 3% by weight, more preferably 0.2% in all monomer units. ~ 2% by weight. By making the content ratio of the monomer unit (C) in the above range, the cold resistance in the case of a rubber cross-linked product is excellent, while the tackiness of acrylic rubber, particularly in the case of a cross-linkable rubber composition. The adhesiveness can be lowered, and as a result, the roll processability can be improved. If the content ratio of the monomer unit (C) is too low, it is difficult to obtain an effect of improving roll processability. On the other hand, if the content is too high, the physical properties of the rubber cross-linked product such as a decrease in elongation may be deteriorated.

  In addition to the monomer units (A) to (C), the acrylic rubber of the present invention has a butenedionic acid monoester monomer unit (D) having an alicyclic structure (hereinafter referred to as “monomer unit (D) as appropriate”). It is preferable to contain. By containing the monomer unit (D), the scorch stability of the acrylic rubber can be improved.

  As the butenedionic acid monoester monomer (d) having an alicyclic structure and forming the monomer unit (D) (hereinafter referred to as “monomer (d)” as appropriate), monocyclopentyl fumarate, Monocyclofumarate such as monocyclohexyl fumarate, monocycloheptyl fumarate, monocyclooctyl fumarate, monomethylcyclohexyl fumarate, mono-3,5-dimethylcyclohexyl fumarate, monodicyclopentanyl fumarate, monoisobonyl fumarate Alkyl ester monomer: Monocycloalkenyl ester of fumarate such as monocyclopentenyl fumarate, monocyclohexenyl fumarate, monocycloheptenyl fumarate, monocyclooctenyl fumarate, monodicyclopentadienyl fumarate, etc. Body: Monocyclopentyl maleate, malein Monocyclohexyl maleate such as monocyclohexyl, monocycloheptyl maleate, monocyclooctyl maleate, monomethylcyclohexyl maleate, mono-3,5-dimethylcyclohexyl maleate, monodicyclopentanyl maleate, monoisobonyl maleate Monomer; Monocycloalkenyl ester maleate such as monocyclopentenyl maleate, monocyclohexenyl maleate, monocycloheptenyl maleate, monocyclooctenyl maleate, dicyclopentadienyl maleate, etc. Of these, a monocycloalkyl ester monomer of fumaric acid is preferable, and monocyclohexyl fumarate is particularly preferable. These may use multiple types together. The monomer (d) acts as an externally crosslinkable monomer that reacts with a crosslinking agent or a vulcanizing agent to form a crosslinked structure after polymerization.

  When the monomer unit (D) is contained, the content ratio of the monomer unit (D) in the acrylic rubber is preferably 0.1 to 20% by weight, more preferably in all monomer units. Is 0.5 to 10% by weight, more preferably 1 to 5% by weight. If the content ratio of the monomer unit (D) is too low, the resulting rubber cross-linked product may not have a sufficient cross-linking density, and good vulcanized physical properties may not be obtained. On the other hand, if the content ratio is too high, the elongation of the resulting rubber cross-linked product may decrease.

  Furthermore, the acrylic rubber of the present invention is a monomer unit other than the monomer units (A) to (D), which can be copolymerized with the monomers (a) to (d) forming these units. It may contain. Other monomers include carboxyl group-containing ethylenically unsaturated monomers other than the monomer (d) forming the monomer unit (D), conjugated diene monomer, and non-conjugated diene monomer. Body, aromatic vinyl monomer, α, β-ethylenically unsaturated nitrile monomer, acrylamide monomer, and other olefin monomers.

  Examples of the carboxyl group-containing ethylenically unsaturated monomer other than the monomer (d) include monomethyl maleate, monoethyl maleate, mono-n-butyl maleate, monomethyl fumarate, monoethyl fumarate, mono-fumarate -Butenedionic acid mono-lower alkyl ester monomers such as butyl; carboxylic acid monomers such as acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, maleic acid, fumaric acid, and citraconic acid; It may be a carboxylic anhydride group, and a carboxylic anhydride monomer such as maleic anhydride or citraconic anhydride can also be used.

Examples of the conjugated diene monomer include 1,3-butadiene, chloroprene, piperylene and the like.
Examples of the non-conjugated diene monomer include 1,4-pentadiene, dicyclopentadiene, ethylidene norbornene, 1,4-hexadiene, norbornadiene, and the like.
Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, divinylbenzene, and the like.

Examples of the α, β-ethylenically unsaturated nitrile monomer include acrylonitrile and methacrylonitrile.
Examples of acrylamide monomers include acrylamide and methacrylamide.
Other olefinic monomers include ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, ethyl vinyl ether, butyl vinyl ether, and the like.

  When the units of these other copolymerizable monomers are contained, the content ratio in the total monomers is preferably 0 to 49.9% by weight, more preferably 0 to 20% by weight.

Method for Producing Acrylic Rubber The acrylic rubber of the present invention comprises the above monomers (a), monomer (b), monomer (c), and monomer (d) used as necessary. And a monomer mixture comprising the above-mentioned monomers copolymerizable with these can be obtained by radical polymerization. As the form of the polymerization reaction, any of an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, and a solution polymerization method can be used. From the viewpoint of easy control of the polymerization reaction, etc., a conventionally known method for producing acrylic rubber It is preferable to use an emulsion polymerization method under normal pressure, which is generally used.

  In the case of polymerization by the emulsion polymerization method, ordinary methods may be used, and conventionally known polymerization initiators, polymerization terminators, emulsifiers and the like that are generally used can be used.

  As polymerization initiators, azo compounds such as azobisisobutyronitrile; organic peroxides such as diisopropylbenzene hydroperoxide, cumene hydroperoxide, benzoyl peroxide; inorganic peroxides such as sodium persulfate and ammonium persulfate And the like. These polymerization initiators can be used alone or in combination of two or more. The amount of the polymerization initiator used is preferably 0.001 to 1.0 part by weight with respect to 100 parts by weight of the monomer mixture.

  Moreover, the organic peroxide and inorganic peroxide as a polymerization initiator can be used as a redox polymerization initiator by combining with a reducing agent. Although it does not specifically limit as a reducing agent used in combination, Compounds containing metal ions in a reduced state such as ferrous sulfate and cuprous naphthenate; Methane compounds such as sodium methanesulfonate; Amines such as dimethylaniline Compound; and the like. These reducing agents can be used alone or in combination of two or more. The amount of the reducing agent used is preferably 0.0003 to 0.1 parts by weight with respect to 100 parts by weight of the peroxide.

  Examples of the polymerization terminator include hydroxylamine, hydroxyamine sulfate, diethylhydroxyamine, hydroxyaminesulfonic acid and its alkali metal salt, sodium dimethyldithiocarbamate and the like. Although the usage-amount of a polymerization terminator is not specifically limited, Usually, it is 0.1-2 weight part with respect to 100 weight part of all the monomers.

  Examples of the emulsifier include nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan alkyl ester; myristic acid, palmitic acid, oleic acid, linolenic acid, and the like. Fatty acid salts, alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, higher alcohol sulfates such as sodium lauryl sulfate, anionic emulsifiers such as alkyl sulfosuccinate; alkyltrimethylammonium chloride, dialkylammonium chloride, benzylammonium chloride, etc. And a cationic emulsifier. Of these, anionic emulsifiers are preferably used. These emulsifiers can be used alone or in combination of two or more. The amount of the emulsifier used is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the monomer mixture.

  The amount of water used is preferably 80 to 500 parts by weight, more preferably 100 to 300 parts by weight with respect to 100 parts by weight of the monomer mixture.

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

  The emulsion polymerization may be any of batch, semi-batch and continuous. The polymerization is usually performed in a temperature range of 0 to 70 ° C, preferably 5 to 50 ° C.

The thus-produced acrylic rubber of the present invention has a Mooney viscosity [ML _{1 + 4} , 100 ° C.] (polymer Mooney) of preferably 10 to 80, more preferably 20 to 70, and particularly preferably 25 to 60.

Crosslinkable rubber composition The crosslinkable rubber composition of this invention mix | blends a crosslinking agent with the said acrylic rubber.

  Examples of the crosslinking agent used in the crosslinkable rubber composition of the present invention include rubbers such as polyvalent amine compounds, polyvalent epoxy compounds, polyvalent isocyanate compounds, aziridine compounds, sulfur compounds, basic metal oxides, and organic metal halides. A conventionally known crosslinking agent which is usually used for crosslinking of the above can be used. Of these, polyvalent amine compounds are preferably used.

The polyvalent amine compound is not particularly limited as long as it is (1) a compound having two or more amino groups, or (2) a compound having two or more amino groups upon crosslinking. A compound in which a plurality of hydrogen atoms of an aromatic hydrocarbon or aromatic hydrocarbon are substituted with an amino group or a hydrazide structure (a structure represented by —CONHNH ₂ , CO represents a carbonyl group) is preferable. Specific examples include an aliphatic polyvalent amine cross-linking agent and an aromatic polyvalent amine cross-linking agent.
Examples of the aliphatic polyvalent amine cross-linking agent include hexamethylene diamine, hexamethylene diamine carbamate, and N, N′-dicinnamylidene-1,6-hexane diamine.
Aromatic polyvalent amine crosslinking agents include 4,4′-methylenedianiline, m-phenylenediamine, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4 ′-(m-phenylenediene. Isopropylidene) dianiline, 4,4 ′-(p-phenylenediisopropylidene) 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, 1,3,5-benzenetriaminomethyl, isophthalic acid dihydrazide; Can be mentioned.

  The blending amount of the crosslinking agent is preferably 0.05 to 20 parts by weight, more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the acrylic rubber. If the blending amount of the crosslinking agent is too small, crosslinking is not sufficiently performed, so that it is difficult to maintain the shape of the resulting rubber crosslinked product, and if it is too large, the resulting rubber crosslinked product becomes too hard and elasticity as a crosslinked rubber, etc. Is damaged.

In the crosslinkable rubber composition of the present invention, in addition to the acrylic rubber and the crosslinking agent, a compounding agent usually used in the rubber processing field can be blended. Examples of such compounding agents include reinforcing fillers such as carbon black and silica; non-reinforcing fillers such as calcium carbonate and clay, antioxidants, light stabilizers, and scorch inhibitors such as monovalent primary amines. , Plasticizers, processing aids, lubricants, adhesives, lubricants, flame retardants, antifungal agents, antistatic agents, colorants, silane coupling agents, crosslinking accelerators, crosslinking aids, crosslinking retarders, etc. . The compounding amount of these compounding agents is not particularly limited as long as it does not impair the object and effect of the present invention, and an amount corresponding to the compounding purpose can be appropriately compounded.

  Moreover, you may further mix | blend rubber | gum other than the acrylic rubber of this invention, an elastomer, resin, etc. in the crosslinkable rubber composition of this invention in the range which does not impair the effect of this invention. For example, natural rubber, polybutadiene rubber, rubbers other than the above-mentioned acrylic rubber of the present invention, polyisoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber; olefin elastomer, styrene elastomer, vinyl chloride elastomer, polyester Elastomers such as polyurethane elastomers, polyamide elastomers, polyurethane elastomers and polysiloxane elastomers; resins such as polyolefin resins, polystyrene resins, polyacrylic resins, polyphenylene ether resins, polyester resins, polycarbonate resins and polyamide resins Etc. can be blended. The total blending amount of the rubber, elastomer and resin is preferably 50 parts by weight or less, more preferably 10 parts by weight or less, and particularly preferably 1 part by weight or less with respect to 100 parts by weight of the acrylic rubber of the present invention. .

  In preparation of the crosslinkable rubber composition of the present invention, the acrylic rubber, the crosslinking agent and other compounding agents may be mixed and kneaded with a Banbury mixer or kneader, and then further kneaded using a kneading roll. preferable. Since the crosslinkable rubber composition of the present invention is produced using the above acrylic rubber, the roll adhesiveness can be lowered. As a result, the composition adheres to the metal during kneading with the kneading roll. It is difficult and has excellent roll processability.

  The order of blending the components is not particularly limited. However, after sufficiently mixing components that are difficult to react or decompose with heat, a crosslinking agent, which is a component that easily reacts or decomposes with heat, does not cause reaction or decomposition. It is preferable to mix in a short time.

The Mooney viscosity [ML _{1 + 4} , 100 ° C.] (compound Mooney) of the crosslinkable rubber composition of the present invention is preferably 20 to 100, more preferably 25 to 80, and particularly preferably 30 to 70. By setting the Mooney viscosity of the crosslinkable rubber composition within the above range, roll adhesiveness can be lowered, and as a result, the crosslinkable rubber composition can be excellent in roll processability.

Rubber cross-linked product The rubber cross-linked product of the present invention is obtained by cross-linking the above cross-linkable rubber composition, and is formed by a molding machine corresponding to a desired shape, for example, an extruder, an injection molding machine, a compressor, a roll or the like. It can be obtained by molding and fixing the shape as a rubber cross-linked product by a cross-linking reaction. In that case, after shaping | molding previously, you may bridge | crosslink, and you may bridge | crosslink simultaneously with shaping | 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 2 hours, preferably 3 minutes to 1 hour. As a heating method, a method used for crosslinking of rubber such as press heating, steam heating, oven heating, hot air heating and the like may be appropriately selected.

  Further, depending on the shape and size of the rubber cross-linked product, even if the surface is cross-linked, it may not be sufficiently cross-linked to the inside. Therefore, secondary cross-linking may be performed by heating. The secondary crosslinking varies depending on the heating method, crosslinking temperature, shape, etc., but is preferably performed for 1 to 48 hours. What is necessary is just to select a heating method and heating temperature suitably.

  Since the rubber cross-linked product of the present invention obtained in this way is obtained using the acrylic rubber of the present invention, at the time of processing, it is excellent in roll processability and is a cross-linked product. It has excellent normal physical properties and cold resistance.

  Therefore, the rubber cross-linked product of the present invention makes use of the above-mentioned properties, O-ring, packing, diaphragm, oil seal, shaft seal, bearing seal, mechanical seal, well head seal, electrical / electronic equipment seal, pneumatic equipment Seal, cylinder head gasket attached to the connecting part between cylinder block and cylinder head, rocker cover gasket attached to the connecting part between rocker cover and cylinder head, attached to the connecting part between oil pan and cylinder block or transmission case Various types of gaskets such as an oil pan gasket, a fuel cell separator gasket, a hard disk drive top cover gasket, and the like mounted between a pair of housings sandwiching a unit cell including a positive electrode, an electrolyte plate, and a negative electrode; It is preferably used Te.

  Further, the rubber cross-linked product of the present invention includes various rolls such as printing rolls, industrial rolls, and office machine rolls; various belts; fuel hoses, turbo air hoses, oil hoses, radiator hoses, heater hoses, water hoses, vacuums. Various hoses such as brake hose, control hose, air conditioner hose, brake hose, power steering hose, air hose, marine hose, riser, flow line; various types such as CVJ boots, propeller shaft boots, constant velocity joint boots, rack and pinion boots, etc. Boots; cushioning materials, dynamic dampers, rubber couplings, air springs, damping materials such as vibration damping materials, rubber parts; dust covers, automotive interior parts, tires, coated cables, shoe soles, electromagnetic shields, flexible printed circuit boards Adhesive such agents, other fuel cell separator can cosmetics, and pharmaceuticals fields of the field in contact with the food, also be used in a wide range of applications such as electronics field.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples. In the following, “part” and “%” are based on weight unless otherwise specified. The test and evaluation were as follows.

Mooney viscosity [ML _{1 + 4} (100 ° C)]
The Mooney viscosity (polymer Mooney) of the acrylic rubber and the Mooney viscosity (Compound Mooney) of the crosslinkable rubber composition were measured according to JIS K6300.

Roll processability When preparing a crosslinkable rubber composition according to the following method, using a metal kneading roll, kneading at a temperature of 50 ° C. for 2 minutes, and further continuing the rotation of the roll, The roll processability was evaluated in three stages as follows.
○: Easy to switch rolls △: There is roll adhesion and difficult to switch ×: Roll adhesion is severe and cannot be switched

For the scorch stable crosslinkable rubber composition, Mooney scorch time (t5) was measured at 125 ° C. according to JIS K6300. The larger the Mooney scorch time (t5), the better the scorch stability.

Normal properties (tensile strength, elongation, 100% tensile stress, hardness)
The crosslinkable rubber composition was press-molded using a mold at 170 ° C. for 20 minutes while applying pressure to obtain a sheet-like cross-linked product having a length of 15 cm, a width of 15 cm, and a thickness of 0.2 cm. The obtained cross-linked product was punched out with a JIS No. 3 dumbbell to prepare a test piece. And using the obtained test piece, according to JIS K6251, the tensile strength, elongation and 100% tensile stress of the rubber cross-linked product, and according to JIS K6253, using the durometer hardness tester type A, Each hardness was measured.

Brittle temperature The brittle temperature was measured according to JIS K6301 using the same sheet-like rubber cross-linked product used for the evaluation of the above-mentioned normal physical properties.

Example 1
In a polymerization reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a decompression device, 200 parts of water, 3 parts of sodium lauryl sulfate, 6 parts of ethyl acrylate, 30 parts of methoxyethyl acrylate, 60 parts of n-butyl acrylate , 1 part of polyethylene glycol dimethacrylate having a weight average molecular weight of 336, and 3 parts of monocyclohexyl fumarate, repeated degassing under reduced pressure and nitrogen substitution to sufficiently remove oxygen, 0.002 part of sodium formaldehyde sulfoxylate and The emulsion polymerization reaction was started at normal pressure and normal temperature by adding 0.005 part of cumene hydroperoxide, and the reaction was continued until the polymerization conversion reached 95%, and the polymerization was terminated by adding a polymerization terminator. The resulting emulsion polymerization solution was coagulated with an aqueous calcium chloride solution, washed with water and dried to obtain acrylic rubber A.

Acrylic rubber A obtained by the above reaction (analysis result by ¹ H-NMR: 6% ethyl acrylate unit, 30% methoxyethyl acrylate unit, 60% butyl acrylate unit, polyethylene glycol dimethacrylate unit having a weight average molecular weight of 336) 1 part and 100 parts monocyclohexyl fumarate unit 3 parts, carbon black (according to ASTM D1765; N550) 60 parts, stearic acid (carbon black dispersant, softener) 2 parts and 4,4′-bis ( 2 parts of α, α-dimethylbenzyl) diphenylamine (anti-aging agent) are kneaded in a Banbury at 50 ° C., and then 0.5 part of hexamethylenediamine carbamate (aliphatic diamine cross-linking agent), di-o-tolylguanidine ( Add 2 parts of crosslinking accelerator) and knead at 50 ° C with a kneading roll. A crosslinkable rubber composition was prepared. At this time, the roll processability was also evaluated according to the above method by further kneading.

  And each evaluation of scorch stability was performed using the obtained crosslinkable rubber composition. Furthermore, the obtained crosslinkable rubber composition was made into a crosslinked product under the above-mentioned conditions, and each evaluation of normal properties (tensile strength, elongation, 100% tensile stress, hardness) and embrittlement temperature of the obtained crosslinked product was performed. It was. The results are shown in Table 1.

Example 2
Acrylic rubber B (each monomer unit) was prepared in the same manner as in Example 1 except that the amount of butyl acrylate used was changed to 58 parts and the amount of polyethylene glycol dimethacrylate having a weight average molecular weight of 336 was changed to 3 parts. The ratios are shown in Table 1.) and each evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 3
Acrylic rubber C (ratio of each monomer unit is shown in Table 1) in the same manner as in Example 1 except that the same amount of ethylene glycol dimethacrylate was used instead of polyethylene glycol dimethacrylate having a weight average molecular weight of 336. And evaluation was conducted in the same manner as in Example 1. The results are shown in Table 1.

Example 4
Except that the amount of methoxyethyl acrylate used was changed to 20 parts and the amount of n-butyl acrylate used was changed to 70 parts, respectively, acrylic rubber D (the ratio of each monomer unit was changed in the same manner as in Example 1). It is shown in Table 1.) was manufactured and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1
The acrylic rubber E (the ratio of each monomer unit was changed in the same manner as in Example 1 except that the amount of n-butyl acrylate used was 61 parts and polyethylene glycol dimethacrylate having a weight average molecular weight of 336 was not used. It is shown in Table 1.) was manufactured and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2
Instead of polyethylene glycol dimethacrylate having a weight average molecular weight of 336, the same amount of trimethylolpropane trimethacrylate was used as in Example 1, except that acrylic rubber F (ratio of monomer units in Table 1) In the same manner as in Example 1, each evaluation was performed. The results are shown in Table 1.

Comparative Example 3
Example 1 except that the amount of methoxyethyl acrylate used was changed to 25 parts, the amount of n-butyl acrylate used was changed to 58 parts, and the amount of polyethylene glycol dimethacrylate having a weight average molecular weight of 336 was changed to 8 parts. In the same manner as above, acrylic rubber G (the ratio of each monomer unit is shown in Table 1) was produced, and each evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 4
In the same manner as in Example 1, except that the amount of ethyl acrylate used was changed to 16 parts, the amount of methoxyethyl acrylate used was changed to 30 parts, and the amount of n-butyl acrylate used was changed to 50 parts. Rubber H (the ratio of each monomer unit is shown in Table 1) was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

表１中、ポリエチレングリコールジメタクリレート単位（＃３３６）は、重量平均分子量３３６のポリエチレングリコールジメタクリレート単位を意味する。

In Table 1, the polyethylene glycol dimethacrylate unit (# 336) means a polyethylene glycol dimethacrylate unit having a weight average molecular weight of 336.

  From Table 1, the crosslinkable rubber composition obtained using the acrylic rubber according to the present invention has good roll processability, and the rubber cross-linked product obtained by cross-linking this has normal properties (tensile strength). , Elongation, 100% tensile stress, hardness) and cold resistance (Examples 1 to 4).

On the other hand, when an acrylic rubber not containing di (meth) acrylic acid ester was used, roll adhesiveness was increased, resulting in poor roll processability (Comparative Example 1).
In addition, when an acrylic rubber containing tri (meth) acrylate is used instead of di (meth) acrylate, and when the content ratio of di (meth) acrylate is too large, elongation is increased. The result was decreased (Comparative Examples 2 and 3).
Furthermore, when the content ratio of the n-butyl acrylate unit was too small, the results were inferior in cold resistance (Comparative Example 4).

Claims (4)

1 to 20% by weight of a (meth) acrylic acid ester monomer unit (A1) represented by the following formula (1), wherein X is an alkyl group having 1 to 3 carbon atoms, (Meth) acrylic acid ester monomer unit (A2) 1 to 39% by weight represented by (1), wherein X is an alkoxyalkyl group having 2 to 3 carbon atoms, and 4 carbon atoms in the following formula (1) (Meth) acrylic acid ester monomer unit (B) having 5 to 89.8% by weight, and di (meth) acrylic acid ester monomer unit having an alkyl group of ˜8 or an alkoxyalkyl group of 4 to 8 carbon atoms (C) have a 0.1-5 wt%,
An acrylic rubber having a total content of 10 to 40% by weight of the monomer unit (A1) and the monomer unit (A2) .

_{(R 1} is a hydrogen atom or a methyl group, X is an alkoxy shear alkyl group of the alkyl group carbon atoms or 2 to 3 1 to 3 carbon atoms) Having a butenedionic acid monoester monomer unit (D) having an alicyclic structure,
The content of the alicyclic structure butenedionic acid monoester monomer unit having a (D) is an acrylic rubber as set forth in claim 1 is 0.1 to 20 wt%. A crosslinkable rubber composition comprising the acrylic rubber according to claim 1 or 2 and a crosslinking agent. A crosslinked rubber product obtained by crosslinking the acrylic rubber composition according to claim 3 .