Acrylic rubber mixture and crosslinkable acrylic rubber composition

Abstract

To suppress significant softening degradation observed at an early stage of thermal oxidative degradation of a crosslinked acryl rubber and suppress deterioration of mechanical strength.SOLUTION: An acryl rubber mixture comprises: a carboxyl group-containing acryl rubber A that comprises anα,β-unsaturated carboxylic acid monomer and an alkyl (meth)acrylate monomer and / or an alkoxyalkyl (meth)acrylate monomer as monomer units; and a carbamate group-containing acryl rubber B that comprises a carbamate group-containing (meth)acrylate monomer represented by a general formula [I] (where, R1: a hydrogen atom or a methyl group and R2: a C1-10 bivalent aliphatic hydrocarbon group) and an alkyl (meth)acrylate monomer and / or an alkoxyalkyl (meth)acrylate monomer as monomer units.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an acrylic rubber mixture and a cross-linkable acrylic rubber composition. More specifically, the present invention relates to an acrylic rubber mixture and a cross-linkable acrylic rubber composition that improve the heat resistance of a cross-linked product and suppress a decrease in mechanical strength. [Background technology]

[0002] From the perspective of global climate change countermeasures and efficient energy use, regulations on emissions of carbon dioxide, NOx gases, and other gases emitted by internal combustion engines, such as automobile engines, are becoming increasingly strict. As a response, automobile engines are required to have higher output, higher thermal efficiency, and reduced and harmless exhaust gases, which has led to a trend toward rising temperatures inside the engine compartment. Accordingly, polymeric materials used in the vicinity, such as rubber and plastics, are required to have even greater heat resistance.

[0003] As a specific example, vehicles equipped with turbocharger systems to improve engine fuel efficiency are becoming more common. The air guided from the turbocharger to the intercooler and engine is at high temperature and pressure, so the rubber hose material that transports this air must have high heat resistance.

[0004] As described above, in response to the demand for higher temperatures and longer life for the polymeric materials used in automobile engines, efforts are being made to improve the heat resistance of the raw rubber itself that makes up the rubber product components, and appropriate antioxidants are being added to the rubber product components.

[0005] Typical antioxidants include phenol-based antioxidants and amine-based antioxidants, and amine-based antioxidants are used particularly for rubber members used in higher temperature environments.

[0006] For example, in the case of acrylic rubber, an amine-based antioxidant, typified by 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, is used as the antioxidant (Patent Documents 1 to 4).

[0007] In addition, in an effort to improve the heat resistance of acrylic rubber itself, the crosslinking monomer has been changed from an active chlorine-containing unsaturated monomer to an α,β-unsaturated carboxylic acid monomer, thereby forming a strong crosslinked structure that can withstand use in high-temperature environments.

[0008] However, even with the improvement of the heat resistance of the raw rubber itself and the addition of amine-based antioxidants, it is not possible to fully satisfy the current demand for heat resistance.

[0009] In recent years, Patent Document 5 describes that phenothiazine-based antioxidants are effective as antioxidants for rubber materials.

[0010] Patent Document 5 describes a rubber material that is excellent in vulcanization properties, mechanical properties, and heat aging properties and is particularly suitable for use as a vibration-proof rubber, and that contains (A) a diene rubber, (B) a bismaleimide compound, and (C) the following phenothiazine compound. TIFF0007812250000001.tif27165R 1 , R 2 : Hydrogen atom, optionally substituted with an aromatic ring C1 to C8 alkyl groups, Alkoxy group, halogen atom, cyano group R 3 : a hydrogen atom, a C1-C6 linear or cyclic alkyl group, vinyl group, aromatic group m, n: 0 to 2 Phenothiazine compounds in which the sulfur atom at the 5-position is -SO2- are also known, and are described in, for example, Patent Document 6.

[0011] Patent Document 6 describes a fused heterocyclic compound represented by the following general formula and an organic material composition containing the same, and states that it is possible to impart high processing stability, heat resistance, and long life to organic materials such as polymers that are susceptible to oxidative, thermal, or light-induced degradation. TIFF0007812250000002.tif28165Y: Chemical single bond, -S(=O)-, -SO2- R a , R b : C1 to C which may have a substituent 30 organic group Z a , Z b : Chemical single bond, -SO2- X 1 , X 2 : Hydrogen atom, halogen atom, alkyl group, cyano group, nitro group, -OR 1 , -O-CO-R 1 , -CO-OR 1 , -O-CO-OR 1 , -NR 2 R 3 , -NR 2 -CO-R 1 , -CO-NR 2 R 3 , -O-CO-NR 2 R 3 , n, m: 0 to 2, but either one is not 0

[0012] Furthermore, in order to prevent the volatilization of amine-based antioxidants from rubber components, studies have been conducted to increase the molecular weight and melting point of the amine-based antioxidants. However, as the molecular weight and melting point of the antioxidant increase, problems arise, such as a decrease in dispersibility in rubber and migration within the rubber.

[0013] In order to prevent the volatilization of antioxidants and extend the life of rubber parts in high-temperature environments, a method of copolymerizing antioxidants having polymerizable unsaturated groups with raw rubber has also been investigated (Patent Document 7).

[0014] For example, Non-Patent Documents 1 and 2 exemplify anti-aging agents having a polymerizable unsaturated group, such as Nocrac G-1 (Ouchi Shinko Chemical Industry Co., Ltd.) and APMA (Seiko Chemical Industry Co., Ltd.). TIFF0007812250000003.tif50168

[0015] However, the radical copolymerization of the above antioxidants with polymerizable unsaturated monomers is practically difficult due to the radical polymerization inhibiting effect of the diphenylamino group.

[0016] Additionally, several methods have been disclosed for introducing diphenylamino structures into elastomeric polymers by modification reactions. For example, a method in which the side chains of an elastomer having olefinic unsaturated groups are hydroformylated and then diphenylamino groups are introduced (Patent Document 8), and a method in which maleic anhydride is added to a diene copolymer in the presence of a free radical generator and then diphenylamino groups are introduced (Patent Document 9) are known. However, these methods require an additional modification step of introducing diphenylamino groups after producing the base copolymer, making them impractical in terms of production costs.

[0017] Furthermore, a method is known in which acrylic rubber is crosslinked in the presence of 4-aminodiphenylamine (Patent Document 10), but there is concern that in this method 4-aminodiphenylamine may inhibit polyamine crosslinking to some extent.

[0018] Conventional technologies cannot fully satisfy today's heat resistance requirements, regardless of whether they are achieved by improving the heat resistance of the raw rubber itself, by improving the performance of various antioxidants, or by chemically bonding heat-aging prevention components to the raw rubber. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] Japanese Patent Application Publication No. 11-21411 [Patent Document 2] WO 2011 / 58918 A1 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-254579 [Patent Document 4] WO 2006 / 001299 A1 [Patent Document 5] JP 2015-227402 A [Patent Document 6] WO 2011 / 093443 A1 [Patent Document 7] Japanese Patent Application Laid-Open No. 2009-209268 [Patent Document 8] Japanese Patent Application Publication No. 4-264106 [Patent Document 9] Japanese Patent Application Publication No. 5-230132 [Patent Document 10] WO 2020 / 158132 A1 [Patent Document 11] JP 2009-036960 A [Patent Document 12] JP 2010-235955 A [Non-patent literature]

[0020] [Non-Patent Document 1] Rubber Chem.Technol., Vol. 46, p. 106 (1973) [Non-patent document 2] Rubber Chem.Technol., Vol. 52, p. 883 (1979) [Non-patent document 3] Journal of Photopolymer Science and Technology, Vol. 18, No. 3, p. 419 (2005) [Non-patent document 4] Material Technology, Vol. 25, No. 6, p. 285 (2007)

[0021] In response to the above problems, the present inventors investigated whether it would be possible to solve the problem of improving the heat resistance of acrylic rubber by introducing a complementary crosslinking system into acrylic rubber. In particular, they investigated how to suppress the significant softening and degradation that occurs in the early stages of thermal oxidative degradation of acrylic rubber, which uses ethyl acrylate as its main raw material. Summary of the Invention [Problem to be solved by the invention]

[0022] The present invention has been made in view of the above-mentioned problems, and has an object to provide an acrylic rubber mixture and a cross-linkable acrylic rubber composition that can suppress the significant softening and deterioration observed in the early stage of thermo-oxidative deterioration of a cross-linked acrylic rubber product and can suppress a decrease in mechanical strength. [Means for solving the problem]

[0023] The object of the present invention is to dibasic acid α,β-unsaturated carboxylic acid or dibasic α,β-unsaturated carboxylic acid monoalkyl ester dibasic acid A carboxyl group-containing acrylic rubber A having monomer units of an α,β-unsaturated carboxylic acid monomer and an alkyl (meth)acrylate monomer and / or an alkoxyalkyl (meth)acrylate monomer, represented by the general formula [I] TIFF0007812250000004.tif39166 (where R 1 is a hydrogen atom or a methyl group, and R 2 This is achieved by an acrylic rubber mixture comprising a carbamate group-containing acrylic rubber B having, as monomer units, a carbamate group-containing (meth)acrylate monomer represented by the formula (I) and an alkyl (meth)acrylate monomer and / or an alkoxyalkyl (meth)acrylate monomer, and a crosslinkable acrylic rubber composition comprising the acrylic rubber mixture and a crosslinking accelerator. [Effects of the Invention]

[0024] The crosslinkable acrylic rubber composition according to the present invention is a crosslinkable acrylic rubber composition according to the present invention. TIFF0007812250000005.tif70156Fmoc: 9-Fluorenylmethyloxycarbonyl group As shown in the figure, during crosslinking, a crosslinked structure is selectively and complementarily formed between the carboxyl group-containing acrylic rubber A and the carbamate group-containing acrylic rubber B, and no crosslinked structure is formed between the acrylic rubbers A themselves or between the acrylic rubbers B themselves. This has the excellent effect of suppressing the significant softening and deterioration that occurs in the early stages of thermal oxidative deterioration of the resulting crosslinked product and making it possible to suppress a decrease in mechanical strength.

[0025] Furthermore, when producing the crosslinkable composition, crosslinking is possible without adding an aromatic or aliphatic polyamine crosslinking agent, so the step of adding a crosslinking agent can be omitted and the risk of poor dispersion of the crosslinking agent in the acrylic rubber can be eliminated.

[0026] Incidentally, a copolymer of a carbamate group-containing (meth)acrylate monomer represented by the above general formula [I] and an alkyl (meth)acrylate monomer such as methyl acrylate or methyl methacrylate is described in Patent Document 11 and Non-Patent Documents 3 and 4, and Patent Document 12 describes that a carboxyl group-containing acrylic rubber can be crosslinked using a dicarbamate ester compound, but there is no teaching or suggestion whatsoever that an acrylic rubber that can achieve the desired heat resistance can be obtained by using these in combination. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a graph showing the strength at break of acrylic rubber over time (solid line: Example 1, dotted line: Comparative Example 1). [Figure 2] 1 is a graph showing the elongation at break of acrylic rubber over time (solid line: Example 1, dotted line: Comparative Example 1). [Figure 3]1 is a graph showing the strength at break of acrylic rubber over time (solid line: Example 2, dotted line: Comparative Example 2). [Figure 4] 1 is a graph showing the elongation at break of acrylic rubber over time (solid line: Example 2, dotted line: Comparative Example 2). DETAILED DESCRIPTION OF THE INVENTION

[0028] The acrylic rubber A constituting the acrylic rubber mixture of the present invention is dibasic acid The monomer units are an α,β-unsaturated carboxylic acid monomer and an alkyl (meth)acrylate monomer and / or an alkoxyalkyl (meth)acrylate monomer. dibasic acid The copolymer used is one in which an α,β-unsaturated carboxylic acid monomer is copolymerized in an amount of 0.1 to 5% by weight, preferably 0.5 to 5% by weight, and an alkyl (meth)acrylate monomer and / or an alkoxyalkyl monomer is copolymerized in an amount of 99.9 to 95% by weight, preferably 99.5 to 95% by weight. Here, (meth)acrylate refers to acrylate or methacrylate.

[0029] The monomer unit of acrylic rubber A dibasic acid Examples of the α,β-unsaturated carboxylic acid monomer include: dibasic acid Examples thereof include α,β-unsaturated carboxylic acids and dibasic α,β-unsaturated carboxylic acid monoalkyl esters.

[0031] Examples of the dibasic α,β-unsaturated carboxylic acid include maleic acid, maleic anhydride, fumaric acid, itaconic acid, and citraconic acid.

[0032] Examples of dibasic α,β-unsaturated carboxylic acid monoalkyl esters include monoalkyl esters of maleic acid, fumaric acid, itaconic acid, and citraconic acid. Specific examples include monomethyl maleate, monoethyl maleate, mono-n-propyl maleate, monoisopropyl maleate, mono-n-butyl maleate, monoisobutyl maleate, mono-n-hexyl maleate, monocyclohexyl maleate, monomethyl fumarate, monoethyl fumarate, mono-n-propyl fumarate, monoisopropyl fumarate, mono-n-butyl fumarate, monoisobutyl fumarate, mono-n-hexyl fumarate, and monocyclohexyl fumarate.

[0033] The alkyl(meth)acrylate monomer and / or alkoxyalkyl(meth)acrylate monomer, which is the monomer unit of the acrylic rubber A, is at least one (meth)acrylate selected from alkyl(meth)acrylates having an alkyl group with 1 to 8 carbon atoms, aralkyl(meth)acrylates having an aralkyl group with 7 to 20 carbon atoms, and alkoxyalkyl(meth)acrylates having an alkoxyalkyl group with 2 to 8 carbon atoms.

[0034] Examples of alkyl(meth)acrylates that can be used include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, n-hexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, and cyclohexyl(meth)acrylate.

[0035] As the aralkyl(meth)acrylate, for example, benzyl(meth)acrylate is used.

[0036] Examples of alkoxyalkyl (meth)acrylates that can be used include methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, n-butoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate, methoxyethoxyethyl (meth)acrylate, and ethoxyethoxyethyl (meth)acrylate.

[0037] In addition to these main components (monomers) of the acrylic elastomer copolymer of the present invention, the following polymerizable unsaturated monomers can be used as secondary components, if necessary.

[0038] Examples of the polymerizable unsaturated monomer include styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, acrylonitrile, methacrylonitrile, acrylic acid amide, vinyl acetate, methyl vinyl ether, ethyl vinyl ether, ethylene, propylene, piperylene, butadiene, isoprene, chloroprene, cyclopentadiene, vinyl chloride, and vinylidene chloride.

[0039] The acrylic rubber A may be, for example, an elastomeric copolymer having ethylene, methyl acrylate and an α,β-unsaturated carboxylic acid monomer as the main components, or a copolymer of ethylene, vinyl acetate and dibasic acid An elastomeric copolymer containing an α,β-unsaturated carboxylic acid monomer as a main component can be used.

[0040] The acrylic rubber B constituting the acrylic rubber mixture of the present invention has, as monomer units, a carbamate group-containing (meth)acrylate monomer represented by general formula [I] and an alkyl (meth)acrylate monomer and / or an alkoxyalkyl (meth)acrylate monomer. These are copolymerized in a monomer ratio of 0.1 to 10% by weight, preferably 0.5 to 5% by weight, of the carbamate group-containing (meth)acrylate monomer and 99.9 to 90% by weight, preferably 99.5 to 95% by weight of the alkyl (meth)acrylate monomer and / or alkoxyalkyl monomer.

[0041] Specific examples of the carbamate group-containing (meth)acrylate monomer that is the monomer unit of acrylic rubber B include: Examples include TIFF0007812250000006.tif115168.

[0042] The carbamate group-containing (meth)acrylate monomer represented by general formula [I] can be easily produced by reacting an isocyanatoalkyl acrylate or an isocyanatoalkyl methacrylate with 9-fluorenylmethanol in the presence of a urethanization reaction catalyst.

[0043] As the urethanization reaction catalyst, an organotin compound, an organotitanium compound, an organozirconium compound, an organobismuth compound, or the like can be used.

[0044] Examples of the organotin compound include dibutyltin dilaurate, tin bis(2-ethylhexanoate), and dibutyltin(2,4-pentanedionate).

[0045] Examples of organic titanium compounds include titanium diisopropoxybis(ethylacetoacetate).

[0046] Examples of organic zirconium compounds include zirconium dibutoxybis(ethyl acetate) and zirconium tetra(acetyl acetate).

[0047] Examples of organic bismuth compounds include bismuth tris(neodecanoate).

[0048] The reaction is carried out in an organic solvent such as benzene, toluene, dioxane, methyl ethyl ketone, or cyclohexane at a temperature of 40 to 80°C.

[0049] The alkyl (meth)acrylate monomer and / or alkoxyalkyl (meth)acrylate monomer that are the monomer units of the acrylic rubber B have the same meaning as the monomer units of the acrylic rubber A.

[0050] Furthermore, as the acrylic rubber B, for example, an elastomeric copolymer having ethylene, methyl acrylate, and a carbamate group-containing (meth)acrylate monomer as the main components, or an elastomeric copolymer having ethylene, vinyl acetate, and a carbamate group-containing (meth)acrylate monomer as the main components, can be used.

[0051] The acrylic rubbers A and B constituting the acrylic rubber mixture of the present invention are produced by a general acrylic rubber copolymerization method. The copolymerization reaction can be carried out by any method such as emulsion polymerization, suspension polymerization, solution polymerization, or bulk polymerization, but emulsion polymerization or suspension polymerization is preferably used, and the reaction is carried out at a temperature of about -10 to 100°C, preferably about 5 to 80°C.

[0052] As the polymerization initiator for the reaction, organic peroxides or hydroperoxides such as benzoyl peroxide, dicumyl peroxide, tert-butyl hydroperoxide, cumyl hydroperoxide, and p-methylene hydroperoxide, diazo compounds such as azobisisobutyronitrile and azobisisobutylamidine, and peroxide salts such as ammonium salts typified by ammonium persulfate, sodium salts, and potassium salts may be used alone or as redox initiators.

[0053] A particularly preferred emulsifier for use in emulsion polymerization is an aqueous solution of an anionic or nonionic surfactant, the pH of which is adjusted with an acid or base as necessary, and which is buffered with an inorganic salt.

[0054] The polymerization reaction is continued until the conversion rate of the monomer mixture reaches 90% or more. The obtained aqueous latex is coagulated by a salt-acid coagulation method, a method using a salt such as calcium chloride, magnesium sulfate, sodium sulfate, or ammonium sulfate, a method using a boron compound such as boric acid or borax, a thermal coagulation method, or a freeze coagulation method, and the obtained copolymer is thoroughly washed with water and dried. This acrylic rubber has a Mooney viscosity (PML) of about 5 to 100, preferably about 20 to 80. 1+4 (100°C).

[0055] The acrylic rubber mixture of the present invention is composed of 10 to 90% by weight, preferably 25 to 75% by weight, of acrylic rubber A and 90 to 10% by weight, preferably 75 to 25% by weight of acrylic rubber B.

[0056] The approximate composition ratio of acrylic rubber A and acrylic rubber B in the acrylic rubber mixture is W A ×w A / M A =W B ×w B / M B These ratios can be adjusted appropriately taking into consideration factors such as the crosslinking rate. W A (Parts by weight): Weight of acrylic rubber A w A (wt%): acrylic rubber A dibasic acid Weight fraction composition of α,β-unsaturated carboxylic acid monomers M A (g / mol): dibasic acid Molecular weight of α,β-unsaturated carboxylic acid monomer W B (Parts by weight): Weight of acrylic rubber B w B (wt%): Carbamate group-containing (meth)acrylate monomer of acrylic rubber B Weight fraction composition of M B (g / mol): Molecular weight of carbamate group-containing (meth)acrylate monomer

[0057] The acrylic rubber mixture can be easily prepared by mixing an aqueous polymer emulsion of acrylic rubber A and an aqueous polymer emulsion of acrylic rubber B in any desired ratio, followed by coagulation with an aqueous electrolyte solution and drying, or by mixing acrylic rubber A and acrylic rubber B using an open roll, pressure kneader, Banbury mixer, or the like.

[0058] The crosslinkable acrylic rubber composition of the present invention is produced by blending a crosslinking accelerator with the prepared acrylic rubber mixture. The crosslinking accelerator may be a guanidine compound, a diazabicycloalkene compound, or an organic acid salt thereof.

[0059] Examples of the guanidine compound include tetramethylguanidine, tetraethylguanidine, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, etc. Preferred are 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, or a combination thereof.

[0060] The diazabicycloalkene compound is preferably 1,8-diazabicyclo[5.4.0]-7-undecene.

[0061] The organic acid salt of the diazabicycloalkene compound is preferably an organic acid salt of 1,8-diazabicyclo[5.4.0]-7-undecene.

[0062] The organic acid used for the organic acid salt of 1,8-diazabicyclo[5.4.0]-7-undecene includes an organic monobasic acid or an organic dibasic acid.

[0063] Examples of organic monobasic acids include n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, n-capric acid, n-lauric acid, p-toluenesulfonic acid, phenol, etc. Examples of organic dibasic acids include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, terephthalic acid, orthophthalic acid, phthalic acid, etc., and monocarboxylic or dicarboxylic acids having 6 to 18 carbon atoms are preferred.

[0064] The crosslinking accelerator is used in an amount of about 0.1 to 5 parts by weight, preferably about 0.5 to 5 parts by weight, per 100 parts by weight of the acrylic rubber mixture. If the amount of crosslinking accelerator is less than this amount, the crosslinking rate may be significantly reduced, and the mechanical properties of the acrylic rubber after crosslinking and after heat aging may be reduced. On the other hand, if more than this amount is used, the compression set resistance of the acrylic rubber may be deteriorated.

[0065] The acrylic rubber composition can be easily produced by mixing the acrylic rubber mixture and the crosslinking accelerator using an open roll, kneader, Banbury mixer or the like.

[0066] The crosslinkable acrylic rubber composition of the present invention may be blended with various additives, as needed, such as a heat anti-aging agent, a filler, a processing aid, a plasticizer, a softener, an anti-aging agent, a colorant, a stabilizer, an adhesion aid, a release agent, an electrical conductivity imparting agent, a thermal conductivity imparting agent, a surface non-stick agent, a tackifier, a flexibility imparting agent, a heat resistance improver, a flame retardant, an ultraviolet absorber, an oil resistance improver, a scorch inhibitor, and a lubricant.

[0067] Examples of fillers include silica such as basic silica and acidic silica, metal oxides such as zinc oxide, calcium oxide, titanium oxide and aluminum oxide; metal hydroxides such as magnesium hydroxide, aluminum hydroxide and calcium hydroxide; carbonates such as magnesium carbonate, aluminum carbonate, calcium carbonate and barium carbonate; silicates such as magnesium silicate, calcium silicate, sodium silicate and aluminum silicate; sulfates such as aluminum sulfate, calcium sulfate and barium sulfate; metal sulfides such as molybdenum disulfide, iron sulfide and copper sulfide; synthetic hydrotalcite, diatomaceous earth, asbestos, lithopone (zinc sulfide / barium sulfide), graphite, carbon black (MT carbon black, SRF carbon black, FEF carbon black, etc.), carbon fluoride, calcium fluoride, coke, quartz fine powder, zinc oxide, talc, mica powder, wollastonite, carbon fiber, aramid fiber, various whiskers, glass fiber, organic reinforcing agents, and organic fillers.

[0068] Examples of processing aids include higher fatty acids such as stearic acid, oleic acid, palmitic acid, and lauric acid; higher fatty acid salts such as sodium stearate and zinc stearate; higher fatty acid amides such as stearic acid amide and oleic acid amide; higher fatty acid esters such as ethyl oleate, higher aliphatic amines such as stearylamine and oleylamine; petroleum waxes such as carnauba wax and ceresin wax; polyglycols such as ethylene glycol, glycerin, and diethylene glycol; aliphatic hydrocarbons such as petrolatum and paraffin; silicone oils, silicone polymers, low-molecular-weight polyethylene, phthalate esters, phosphate esters, rosin, (halogenated) dialkylamines, (halogenated) dialkylsulfones, and surfactants.

[0069] Examples of plasticizers include epoxy resins, phthalic acid derivatives, and sebacic acid derivatives; examples of softeners include lubricating oils, process oils, coal tar, castor oil, and calcium stearate; and examples of antioxidants include phenylenediamines, phosphates, quinolines, cresols, phenols, and dithiocarbamate metal salts.

[0070] The above compounding ingredients, which are used as needed, are blended into the crosslinkable acrylic rubber composition of the present invention, which comprises an acrylic rubber mixture and a crosslinking accelerator, and mixed using a Banbury mixer, a pressure kneader, an open roll, etc. Crosslinking of the resulting crosslinkable mixture is carried out by primary crosslinking at about 120 to 250°C for about 1 to 60 minutes, and, if necessary, oven crosslinking (secondary crosslinking) at about 120 to 200°C for about 1 to 20 hours. [Example]

[0071] The present invention will now be described in detail with reference to examples, although the present invention, including its effects, is not limited to these examples.

[0072] Reference example 9FMM Manufacturing TIFF0007812250000007.tif53166 26.3 g (134 mmol) of 9-fluorenylmethanol, 25.0 g (161 mmol) of 2-isocyanatoethyl methacrylate, 1.1 g of dibutyltin dilaurate, and 440 ml of benzene were placed in a 500 ml four-neck flask equipped with a magnetic stirrer, a thermometer, a nitrogen gas inlet and outlet, and a reflux condenser, and the mixture was allowed to react at 80°C for 2 hours under a nitrogen gas atmosphere.

[0073] After the reaction mixture was cooled to room temperature, 50 mg of p-methoxyphenol was added, and the benzene was then distilled off under reduced pressure to give 67.2 g of crude reaction product, which was recrystallized from 600 ml of ethanol to give 41.1 g (87% yield) of 9FMM as colorless crystals. TIFF0007812250000008.tif52129 1 H-NMR (400MHz, Acetone d6, δ ppm): 1.91 (s, 3H, CH2=C(C H 3)-C(=O)-O-) 3.47 (q, 2H, J=5.6Hz, -O-CH2C H 2-NH-C(C=O)-) 4.21 (t, 2H, J=5.6Hz, -OC H 2CH2-NH-C(C=O)-) 4.23 (t, 1H, J=7.2Hz, -C(=O)-OCH2-C H -Ar2) 4.35 (d, 2H, J=7.2Hz, -C(=O)-OC H 2-CH-Ar2) 5.62 (s, 1H, relative to carbonyl group trans-C H 2=C(CH3)-C(=O)-O-) 6.10 (s, 1H, for carbonyl groups cis-C H 2=C(CH3)-C(=O)-O-) 6.73 (brs, 1H, -O-CH2CH2-N H -C(C=O)- 7.32 (t, 2H, J=7.6Hz, Ar-Ha) 7.41 (t, 2H, J=7.6Hz, Ar-Hb) 7.68 (d,2H, J=7.6Hz, Ar-Hc) 7.86 (d,2H, J=7.6Hz, Ar-Hd)

[0074] Example 1 [Production of acrylic rubber a] In a separable flask equipped with a thermometer, a stirrer, a nitrogen gas inlet tube, and a Dimroth condenser, Water 187 parts by weight Sodium lauryl sulfate 2 〃 Polyoxyethylene lauryl ether 2 Charged monomer mixture Ethyl acrylate (EA) 98.6 〃 9FMM 1.4 〃 After the oxygen in the system was thoroughly removed by nitrogen gas replacement, Sodium formaldehyde sulfoxylate 0.008 parts by weight (Fujifilm Wako Pure Chemical Industries Rongalit) Tertiary butyl hydroperoxide 0.0047 〃 (NOF Products Perbutyl H69) Acetic acid 0.67 〃 The polymerization reaction was initiated at room temperature by adding the above and continued until the polymerization conversion rate reached 90% or more. A portion of the resulting aqueous polymerization emulsion a (rubber solids content 32% by weight) was coagulated with a 10% by weight aqueous sodium sulfate solution, then washed with water and dried to obtain acrylic rubber a.

[0075] Mooney viscosity PML of the obtained acrylic rubber a 1+4 (100℃) was 48. Also, the mole fraction composition is 1 Calculation using H-NMR (400 MHz, CD3C(=O)CD3, δ ppm according to the following formula revealed that 9FMM was 0.40 mol % and EA was 99.60 mol %. α: Integrated value of the signal from 6.4 to 8.1 ppm β: Integrated value of the signal between 3.2 and 5.0 ppm 9FMM (mol%) = 200 × α / (9β-5α) EA (mol%) = 100-9FMM (mol%) The weight fraction composition was calculated using the following formula, and was found to be 9FMM: 1.4% by weight, and EA: 98.6% by weight. 9FMM(wt%)=(9FMM(mol%)×351.4×100) / [9FMM(mol%)× 351.4 + ((EA (mol%)) × 100.5) EA (wt%) = 100 - 9FMM (wt%)

[0076] [Production of acrylic rubber b] Ethyl acrylate [EA] 99.2 parts by weight Mono-n-butyl fumarate [MBF] 0.8 % The same procedure as in the production of acrylic rubber a was carried out except that a charged monomer mixture consisting of the above was used and acetic acid was not used, to obtain aqueous polymerization emulsion b (rubber solid content 32% by weight) and acrylic rubber b. The Mooney viscosity PML of the obtained acrylic rubber b 1+4(100°C) was 32. Furthermore, the MBF content (wt%) was calculated by measuring the acid value of acrylic rubber b, and was found to be 0.6 wt%.

[0077] [Production of acrylic rubber mixture I] Equal weights of aqueous polymer emulsion a and aqueous polymer emulsion b were mixed, coagulated with a 10% by weight aqueous solution of sodium sulfate, washed with water, and dried to obtain a mixture of acrylic rubbers a and b, each containing 50% by weight of acrylic rubber a and b. The Mooney viscosity PML of the obtained acrylic rubber mixture I was 1+4 (100℃) was 37.

[0078] For 100 parts by weight of the obtained acrylic rubber mixture I, FEF Carbon Black (Tokai Carbon Products Seast GSO) 60 Stearic acid (Miyoshi Oil Products TST) 1 〃 Polyoxyethylene stearyl ether phosphate 0.5% (Toho Chemical Industry Products Phosphanol RL-210) Crosslinking accelerator (Vulcofac ACT55, product of Safic-Alcan) 1 Antioxidant (4,4'-bis(α,α-dimethylbenzyl 2 ) Diphenylamine: Ouchi Shinko Chemical Industry Products Nocrac CD) First, the acrylic rubber mixture I, FEF carbon black, stearic acid, and polyoxyethylene stearyl ether phosphate were mixed in a Banbury mixer, and then the remaining components were further mixed using an open roll to obtain an acrylic rubber composition.

[0079] The obtained acrylic rubber composition was subjected to primary crosslinking at 180°C for 8 minutes using a 100-ton press molding machine, and further subjected to oven crosslinking at 175°C for 4 hours to obtain a sheet-like crosslinked product having a thickness of approximately 2 mm.

[0080] The crosslinking characteristics of the acrylic rubber composition and the physical properties of the crosslinked product were measured as follows. Mooney scorch test: JIS K6300-1 compliant (125°C) Minimum Mooney viscosity measured using Mooney Viscometer AM-3 manufactured by Toyo Seiki Seisakusho Co., Ltd. (ML min) and scorch time (t5) values ​​were measured. Crosslinking test: JIS K6300-2 compliant (180°C, 12 minutes) Using a rotorless rheometer RLR-3 manufactured by Toyo Seiki Seisakusho, ML, MH, tc(10) and tc(90) values ​​were measured. ML: Minimum torque MH: Maximum torque tc(10): Time required for the cross-linking torque to reach ML + (MH-ML) × 0.1 tc(90): Time required for the cross-linking torque to reach ML + (MH-ML) × 0.9 Normal physical properties: Measured on post-cure sheets in accordance with JIS K6251 and JIS K6253 Air heating aging test: Measured on post-cure sheet in accordance with JIS K6257 (175℃: 250 hours, 500 hours, 750 hours, 1000 hours)

[0081] Comparative Example 1 In Example 1, the same amount (100 parts by weight) of acrylic rubber b obtained in Example 1 was used instead of acrylic rubber mixture I, and hexamethylenediamine carbamate (Unimatec product Cheminox) was newly used. AC-6F ) was added in an amount of 0.3 parts by weight.

[0082] Example 2 [Production of acrylic rubber c] Ethyl acrylate [EA] 97.2 % 9FMM 2.8 〃 The same procedure as in the production of acrylic rubber a was carried out except that a charged monomer mixture consisting of the following was used, to obtain aqueous polymerization emulsion c (rubber solid content 32% by weight) and acrylic rubber c. The Mooney viscosity PML of the obtained acrylic rubber c was 1+4 (100℃) was 47.

[0083] The molar fraction composition of acrylic rubber c was 9FMM: 0.80 mol % and EA: 99.20 mol %, and the weight fraction composition was 9FMM: 2.7 wt % and EA: 97.3 wt %.

[0084] [Production of acrylic rubber d] Ethyl acrylate [EA] 98.4 parts by weight Mono-n-butyl fumarate [MBF] 1.6 〃 The same procedure as in the production of acrylic rubber b was carried out except that a charged monomer mixture consisting of the following was used, to obtain aqueous polymerization emulsion d (rubber solid content 32% by weight) and acrylic rubber d. The Mooney viscosity PML of the obtained acrylic rubber d was 1+4 (100°C) was 36. Furthermore, the MBF content (wt%) was calculated by measuring the acid value of acrylic rubber d, and was found to be 1.2 wt%.

[0085] [Production of Acrylic Rubber Mixture II] Equal weights of aqueous polymer emulsion c and aqueous polymer emulsion d were mixed, coagulated with a 10% by weight aqueous solution of sodium sulfate, washed with water, and dried to obtain a mixture of acrylic rubbers c and d, each containing 50% by weight of acrylic rubber c and d. The Mooney viscosity PML of the resulting acrylic rubber mixture II was 1+4 (100℃) was 39.

[0086] In Example 1, the same amount (100 parts by weight) of acrylic rubber mixture II was used in place of acrylic rubber mixture I to obtain an acrylic rubber composition and a cross-linked product.

[0087] Comparative Example 2 In Comparative Example 1, the same amount (100 parts by weight) of acrylic rubber d obtained in Example 2 was used in place of acrylic rubber b, and 0.6 parts by weight of hexamethylenediamine carbamate (Unimatec product Cheminox AC6F) was further added.

[0088] The results obtained in the above examples and comparative examples are shown in the following table. table Measurement results Example 1 Comparative Example 1 Example 2 Comparative Example 2 Mooney scorch test (125℃) ML min (pts) 67 69 73 63 t5 (min) 3.2 2.8 3.1 2.3 Cross-linking test (180℃) tc(10) (min) 0.58 0.49 0.48 5.01 tc(90) (min) 5.96 5.16 5.83 5.16 ML (N m) 0.26 0.27 0.26 0.27 MH (N·m) 0.60 0.64 0.86 1.00 Normal state physical properties (post cure) Hardness (Duro A) 61 61 68 65 100% Modulus (MPa) 3.0 2.1 7.9 5.9 Breaking strength (MPa) 14.5 13.9 16.3 16.9 Elongation at break (%) 370 400 220 250 Heat aging test (175℃, 250 hours) Hardness (Duro A) 67 67 76 73 100% Modulus (MPa) 2.0 1.2 5.6 3.1 Breaking strength (MPa) 6.6 3.1 10.9 9.3 Elongation at break (%) 420 830 210 350 Heat aging test (175℃, 500 hours) Hardness change (Duro A) 72 67 78 77 100% Modulus (MPa) 1.5 0.9 4.4 2.6 Breaking strength (MPa) 3.3 0.8 7.3 5.4 Elongation at break (%) 460 1700 230 400 Heat aging test (175℃, 750 hours) Hardness (Duro A) 74 77 84 82 100% Modulus (MPa) 1.5 1.2 3.9 2.7 Breaking strength (MPa) 1.7 0.4 5.4 3.7 Elongation at break (%) 490 1400 230 380 Heat aging test (175℃, 1000 hours) Hardness (Duro A) 81 82 90 89 100% Modulus (MPa) 2.1 1.7 4.7 3.9 Breaking strength (MPa) 1.6 1.5 5.0 3.9 Elongation at break (%) 450 980 190 210

Claims

1. A carboxyl group-containing acrylic rubber A having, as monomer units, a dibasic α,β-unsaturated carboxylic acid monomer which is a dibasic α,β-unsaturated carboxylic acid or a dibasic α,β-unsaturated carboxylic acid monoalkyl ester, and an alkyl (meth)acrylate monomer and / or an alkoxyalkyl (meth)acrylate monomer; (where R 1 is a hydrogen atom or a methyl group, and R 2 an acrylic rubber mixture comprising a carbamate group-containing acrylic rubber B having, as monomer units, a carbamate group-containing (meth)acrylate monomer represented by the formula (I) and an alkyl (meth)acrylate monomer and / or an alkoxyalkyl (meth)acrylate monomer, wherein R is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms;

2. 2. The acrylic rubber mixture according to claim 1, wherein the acrylic rubber A is 10 to 90% by weight and the acrylic rubber B is 90 to 10% by weight, where the total amount of the acrylic rubber A and the acrylic rubber B is 100.

3. A crosslinkable acrylic rubber composition comprising 100 parts by weight of the acrylic rubber mixture according to claim 1 or 2 and 0.1 to 5 parts by weight of a crosslinking accelerator blended therein.

4. 4. The crosslinkable acrylic rubber composition according to claim 3, wherein the crosslinking accelerator is 1,8-diazabicyclo[5.4.0]-7-undecene or an organic acid salt thereof.

5. 5. The crosslinkable acrylic rubber composition according to claim 3, wherein no aromatic or aliphatic polyamine crosslinking agent is blended.

6. A crosslinked product of the crosslinkable acrylic rubber composition according to any one of claims 3 to 5.

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