Rubber composition and cured product thereof

Abstract

Provided is a rubber composition capable of forming a cured product having high strength. The rubber composition comprises: an acrylic rubber that is a copolymer of a monomer containing an alkyl (meth)acrylate; silica; and a polyorganosiloxane having 2 or more amino groups per molecule.

Description

Rubber composition and cured product thereof

[0001] The present invention relates to a rubber composition and a cured product thereof.

[0002] Cured products of rubber compositions containing acrylic rubber have excellent physical properties such as heat resistance, oil resistance, mechanical properties, and compression set properties, and are therefore widely used as materials for hose components, seal components, gasket components, and the like in automobile engine bays. In recent years, these automobile components have been required to have higher reliability due to the influence of exhaust gas countermeasures and higher engine power output. In particular, these components are required to have excellent strength, elongation, and compression set properties.

[0003] For example, US Pat. No. 5,999,623 discloses a rubber composition that contains a white filler and can be processed to form a cured product having good mechanical properties.

[0004] Patent No. 6967459

[0005] An object of the present invention is to provide a rubber composition that can form a cured product having high strength.

[0006] The present invention includes the following embodiments.

[0007] [1] A rubber composition comprising: an acrylic rubber that is a copolymer of a monomer containing an alkyl (meth)acrylate; silica; and a polyorganosiloxane having two or more amino groups per molecule.

[0008] [2] The rubber composition according to [1], wherein the acrylic rubber is a carboxyl group-containing acrylic rubber that is a copolymer of a monomer containing an alkyl (meth)acrylate and a carboxyl group-containing monomer.

[0009] [3] The rubber composition according to [1] or [2], wherein the acrylic rubber is a carboxyl group-containing acrylic rubber that is a copolymer of monomers including an alkyl (meth)acrylate, a carboxyl group-containing monomer, and an olefin.

[0010] [4] The rubber composition according to [1], wherein the acrylic rubber is an epoxy group-containing acrylic rubber that is a copolymer of a monomer containing an alkyl (meth)acrylate and an epoxy group-containing monomer.

[0011] [5] The rubber composition according to [4], wherein the acrylic rubber is an epoxy group-containing acrylic rubber that is a copolymer of monomers containing an alkyl (meth)acrylate, an epoxy group-containing monomer, an olefin, and a vinyl carboxylate.

[0012] [6] The rubber composition according to [3] or [5], wherein the olefin is at least one selected from the group consisting of ethylene, butadiene, and isoprene.

[0013] [7] The BET specific surface area of ​​the silica is 100 to 130 m ２ The rubber composition according to any one of [1] to [6], wherein the elastic modulus is 1 / g.

[0014] [8] The rubber composition according to any one of [1] to [7], wherein the alkyl moiety of the alkyl (meth)acrylate has 1 to 4 carbon atoms.

[0015] [9] The rubber composition according to any one of [1] to [8], wherein the polyorganosiloxane has the following structural unit (I): [R １ ｘ R ａ SiO （４－（ｘ＋ａ））／２ (I) (In formula (I), x is 1, 2 or 3, a is 0, 1 or 2, x+a<4, each R is independently methyl, ethyl, propyl, phenyl or hydroxy, and R １ are each independently NH ２ is a monovalent organic residue having a group.)

[0016]

[10] The rubber composition according to any one of [1] to [9], wherein the mass ratio of the silica to the acrylic rubber (silica / acrylic rubber) is 0.2 to 1.0.

[0017]

[11] The rubber composition according to any one of [1] to

[10] , wherein the mass ratio of the polyorganosiloxane to the acrylic rubber (polyorganosiloxane / acrylic rubber) is 0.005 to 0.08.

[0018]

[12] The rubber composition according to any one of [1] to

[11] , wherein the mass ratio of the polyorganosiloxane to the silica (polyorganosiloxane / silica) is 0.01 to 0.3.

[0019]

[13] A cured product obtained by curing the rubber composition according to any one of [1] to

[12] .

[0020]

[14] A hose, seal, or gasket comprising the cured product according to

[13] .

[0021] According to the present invention, it is possible to provide a rubber composition that can form a cured product having high strength.

[0022] The rubber composition according to this embodiment contains an acrylic rubber that is a copolymer of a monomer containing alkyl (meth)acrylate, silica, and a polyorganosiloxane having two or more amino groups per molecule.

[0023] The polyorganosiloxane having two or more amino groups per molecule contained in the rubber composition according to this embodiment is highly compatible with acrylic rubber, which is a copolymer of a monomer containing alkyl (meth)acrylate, and is therefore presumably improving the dispersibility of silica in the rubber composition. When the rubber composition is cured, the amino groups of the polyorganosiloxane bond with the acrylic rubber, positioning the siloxane skeleton in the vicinity of the silica. The high dispersibility of the silica is thought to improve the strength of the resulting cured product. This also allows the cured product to have high elongation. Furthermore, the cured product can have high compression set properties comparable to those of conventional rubber compositions using carbon black or cured rubber compositions using silane coupling agents containing amino or epoxy groups.

[0024] (Acrylic Rubber) The rubber composition according to this embodiment contains an acrylic rubber that is a copolymer of a monomer containing an alkyl (meth)acrylate. "Alkyl (meth)acrylate" refers to alkyl acrylate and alkyl methacrylate. Examples of alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-methylpentyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, and n-octadecyl (meth)acrylate. These may be used alone or in combination of two or more.

[0025] Among these, from the viewpoint of a balance between strength, oil resistance, and cold resistance, alkyl (meth)acrylates in which the alkyl moiety has 1 to 4 carbon atoms are preferred. Specifically, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate are preferred.

[0026] The monomers constituting the copolymer preferably contain 60 to 99% by mass of alkyl (meth)acrylate, more preferably 70 to 99% by mass, and even more preferably 80 to 98% by mass.

[0027] The monomer preferably further includes a carboxyl group-containing monomer or an epoxy group-containing monomer in addition to the alkyl (meth)acrylate. That is, the acrylic rubber according to this embodiment is preferably a carboxyl group-containing acrylic rubber that is a copolymer of a monomer including an alkyl (meth)acrylate and a carboxyl group-containing monomer, or an epoxy group-containing acrylic rubber that is a copolymer of a monomer including an alkyl (meth)acrylate and an epoxy group-containing monomer. The carboxyl group-containing monomer and the epoxy group-containing monomer function as crosslinking monomers (monomers having functional groups that constitute crosslinking points).

[0028] Examples of carboxyl group-containing monomers include acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, itaconic acid, monoalkyl maleate, monoalkyl fumarate, monocyclohexyl maleate, monocyclohexyl fumarate, cinnamic acid, etc. Examples of epoxy group-containing monomers include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether, etc. These may be used alone or in combination of two or more.

[0029] When the monomers constituting the copolymer include a carboxyl group-containing monomer or an epoxy group-containing monomer, from the viewpoint of the balance between strength and elongation, the monomers preferably contain the carboxyl group-containing monomer or the epoxy group-containing monomer in an amount of 0.1 to 5 mass %, more preferably 0.5 to 3 mass %, and even more preferably 1 to 2 mass %.

[0030] The monomer preferably further contains an olefin in addition to an alkyl (meth)acrylate, a carboxyl group-containing monomer, or an epoxy group-containing monomer. That is, the acrylic rubber according to this embodiment is preferably a carboxyl group-containing acrylic rubber that is a copolymer of a monomer containing an alkyl (meth)acrylate, a carboxyl group-containing monomer, and an olefin, or an epoxy group-containing acrylic rubber that is a copolymer of a monomer containing an alkyl (meth)acrylate, an epoxy group-containing monomer, and an olefin. The olefin can improve the mechanical properties and cold resistance of the cured product.

[0031] Examples of olefins include ethylene, butadiene, and isoprene. These may be used alone or in combination of two or more. Among these, ethylene is preferred as the olefin because it does not contain a double bond, which can cause a decrease in heat resistance after the reaction.

[0032] When the monomer constituting the copolymer contains an olefin, the monomer preferably contains 0.1 to 5 mass %, more preferably 0.3 to 4 mass %, and even more preferably 0.5 to 2 mass % of the olefin, from the viewpoint of the mechanical properties of the cured product, etc. Examples of carboxyl group-containing acrylic rubbers that are copolymers of monomers containing alkyl (meth)acrylate, a carboxyl group-containing monomer, and an olefin include commercially available products such as Denka ER A322 (trade name, manufactured by Denka Co., Ltd.) and Denka ER A413 (trade name, manufactured by Denka Co., Ltd.).

[0033] When the monomers include an alkyl (meth)acrylate, an epoxy group-containing monomer, and an olefin, the monomers preferably further include a vinyl carboxylate. That is, the acrylic rubber according to this embodiment is preferably an epoxy group-containing acrylic rubber that is a copolymer of monomers including an alkyl (meth)acrylate, an epoxy group-containing monomer, an olefin, and a vinyl carboxylate. The vinyl carboxylate can improve the mechanical properties of the cured product.

[0034] Examples of vinyl carboxylates include vinyl acetate, vinyl propionate, vinyl 2-ethylhexanoate, vinyl laurate, and vinyl neodecanoate. These may be used alone or in combination of two or more. Among these, vinyl acetate is preferred as the vinyl carboxylate from the viewpoint of strength.

[0035] When the monomer constituting the copolymer contains vinyl carboxylate, the monomer preferably contains 1 to 20 mass %, more preferably 3 to 17 mass %, and even more preferably 5 to 15 mass % of vinyl carboxylate, from the viewpoint of the mechanical properties of the cured product, etc. Examples of epoxy group-containing acrylic rubbers that are copolymers of monomers containing alkyl (meth)acrylate, epoxy group-containing monomer, olefin, and vinyl carboxylate include commercially available products such as Denka ER 5300 (trade name, manufactured by Denka Co., Ltd.).

[0036] The acrylic rubber can be obtained by copolymerizing the above-mentioned monomers by a known method such as emulsion polymerization, suspension polymerization, solution polymerization, or bulk polymerization.

[0037] (Silica) The rubber composition according to the present embodiment contains silica as a filler. By using silica as a filler, the dispersibility of the filler in the rubber composition according to the present embodiment is improved, and the resulting cured product has high strength and elongation. The silica is not particularly limited, but examples thereof include wet silica, dry silica, and silica fume.

[0038] The BET specific surface area of ​​the silica is 100 to 130 m ２ / g. The BET specific surface area of ​​the silica is preferably 100 to 130 m ２ By keeping the BET specific surface area within the range of 1 / g, it is possible to suppress the aggregation of silica and to fully exhibit the reinforcing properties of silica, thereby enabling the resulting cured product to have high strength. The BET specific surface area is a value measured by the BET method.

[0039] In the rubber composition according to the present embodiment, the mass ratio of silica to acrylic rubber (silica / acrylic rubber) is preferably 0.2 to 1.0, more preferably 0.3 to 0.8, and even more preferably 0.4 to 0.6, from the viewpoint of improving the strength and elongation of the cured product.

[0040] (Polyorganosiloxane) The rubber composition according to this embodiment contains a polyorganosiloxane having two or more amino groups per molecule. Conventionally, when silica is used as a filler in rubber compositions containing acrylic rubber, a silane coupling agent having an amino group or an epoxy group is used in combination. In the rubber composition according to this embodiment, by using a polyorganosiloxane having two or more amino groups per molecule instead of the silane coupling agent, a cured product with excellent strength can be formed. Since the polyorganosiloxane has high compatibility with acrylic rubber, which is a copolymer of a monomer containing alkyl (meth)acrylate, it is presumed that the dispersibility of silica is improved, resulting in improved strength of the cured product. Furthermore, the cured product also has good elongation and compression set properties.

[0041] The polyorganosiloxane having two or more amino groups per molecule preferably has the following structural unit (I) from the viewpoint of improving the strength of the cured product. １ ｘ R ａ SiO （４－（ｘ＋ａ））／２ (I) (In formula (I), x is 1, 2 or 3, a is 0, 1 or 2, x+a<4, each R is independently methyl, ethyl, propyl, phenyl or hydroxy, and R １ are each independently NH ２ is a monovalent organic residue having a group.)

[0042] In the formula (I), x is preferably 1. Furthermore, a is preferably 1 or 2, more preferably 1. R is preferably methyl or hydroxy, more preferably methyl. R １ For example, -R ２ -NH ２ , -R ２ -N(R ３ )-NH ２ , -R２ -N(R ３ )-R ４ -NH ２ Here, R ２ and R ４ are each independently an alkylene or alkyleneoxy group having 1 to 20 carbon atoms, preferably an alkylene group having 1 to 5 carbon atoms. ３ is hydrogen or an alkyl group having 1 to 5 carbon atoms.

[0043] R １ is -R ２ -NH ２ Preferably, R ２ is preferably an alkylene group having 1 to 5 carbon atoms, more preferably an alkylene group having 2 to 4 carbon atoms, and particularly preferably an aminopropyl group.

[0044] At least two amino groups per molecule of polyorganosiloxane have different R １ It is preferable that the aryl group is located in the aryl group, and more preferable that the aryl group is located in a different structural unit (I). Ｄ It is more preferred that the ion beam is located at

[0045] A preferred structural unit (I) in which x=1 is the structural unit I in which a=1. Ｄ [R １ RSiO ２／２ ] (I Ｄ ), or structural unit I where a=2 Ｍ [R １ R ２ SiO １／２ ] (I Ｍ )

[0046] In addition to the structural unit (I), the polyorganosiloxane according to this embodiment contains the following structural unit (II Ｄ ) may further comprise [R' ２ SiO ２／２ ] (II Ｄwherein R' is the same or different groups (preferably the same groups) and is a linear, branched, or cyclic organic residue that can be bonded via an oxygen atom. R' is preferably methyl, ethyl, propyl, or phenyl, and particularly preferably methyl.

[0047] In addition to the structural unit (I), the polyorganosiloxane according to this embodiment contains the following structural unit (III Ｍ ) may further comprise [R'' ３ SiO １／２ ] (III Ｍ Here, R" may be the same or different groups and may be hydroxy, linear, branched, or cyclic organic residues that can be bonded via an oxygen atom. R" is preferably hydroxy, methyl, ethyl, propyl, or phenyl, and particularly preferably hydroxy or methyl. For example, R" may be the same group and may be methyl. Also, the structural unit (III) Ｍ ) is [(CH ３ ) ２ (HO)SiO １／２ ] can be.

[0048] For example, a preferred structure of the polyorganosiloxane according to this embodiment is as follows: Ｄ ] ｍ [I Ｍ ] ｎ [II Ｄ ] ｏ [III Ｍ ] （２－ｎ） where m is in the range of 0 to 40, and n can be 0, 1, or 2, provided that m+n is at least 2, and preferably m+n is in the range of up to 20. o is in the range of 0 to 1000. m+o+2 is at least 3.

[0049] Examples of commercially available polyorganosiloxanes having the structural unit (I) include Struktol HT750, HT740, and HT760 (trade names, manufactured by Struktol Co., Ltd.), KF-864, KF-865, KF-868, and KF-8015 (trade names, manufactured by Shin-Etsu Silicones Co., Ltd.), DOWSIL BY 16-213 FLUID (trade name, manufactured by Dow), AMS-132, AMS-152, AMS-162, AMS-163, AMS-191, and AMS-1203 (trade names, manufactured by Gelest Co., Ltd.), which have the structure of the following formula (A):

[0050]

[0051] The mass ratio of the polyorganosiloxane to the acrylic rubber (polyorganosiloxane / acrylic rubber) is preferably 0.005 to 0.08, more preferably 0.007 to 0.07, and even more preferably 0.01 to 0.06, from the viewpoint of improving the strength and elongation of the cured product. The mass ratio of the polyorganosiloxane to the silica (polyorganosiloxane / silica) is preferably 0.01 to 0.3, more preferably 0.02 to 0.2, and even more preferably 0.02 to 0.1, from the viewpoint of improving the strength and elongation of the cured product.

[0052] (Other Components) The rubber composition according to the present embodiment may contain other components in addition to the acrylic rubber, silica, and polyorganosiloxane described above. Examples of other components include antioxidants, lubricants, vulcanizing agents, vulcanization accelerators, vulcanization retarders, plasticizers, and fillers.

[0053] (Cured Product) The cured product according to this embodiment is obtained by curing the rubber composition according to this embodiment. Since the cured product is a cured product of the rubber composition according to this embodiment, it has particularly excellent strength. Therefore, the cured product can be suitably used for hoses, seals, gaskets, etc.

[0054] The following examples are provided to further illustrate the present invention, but are not intended to limit the scope of the invention. The tensile strength, elongation, and compression set of the cured product were measured by the following methods.

[0055] [Tensile Strength] The tensile strength of the cured product was measured in accordance with JIS K6251.

[0056] [Elongation] The elongation of the cured product was measured in accordance with JIS K6251.

[0057] [Compression Set] The compression set of the cured product was measured at 175°C for 72 hours in accordance with JIS K6262.

[0058] Example 1 A rubber composition was prepared by mixing the following components: Acrylic rubber: Denka ER A322 (trade name, manufactured by Denka Co., Ltd.): 100 parts by mass Silica: Nipsil ER (trade name, manufactured by Tosoh Silica Corporation, BET specific surface area: 100 m ２ / g): 50 parts by mass Polyorganosiloxane: Struktol HT750 (trade name, manufactured by Struktol): 2 parts by mass Antiaging agent: DCD (Nauguard #445 manufactured by S.I. Group Co., Ltd.): 1 part by mass Lubricant: stearic acid: 1 part by mass Lubricant: stearylamine: 0.3 parts by mass Vulcanizing agent: hexamethylenediamine carbamate: 0.6 parts by mass Vulcanization accelerator: Rhenogran XLA-60 (trade name, manufactured by Lanxess): 1.2 parts by mass Denka ER A322 contains, as a polymer composition, 82 parts by mass of ethyl acrylate, 17 parts by mass of butyl acrylate, 1 part by mass of ethylene, and 2 parts by mass of a carboxyl group-containing monomer.

[0059] The rubber composition was kneaded using a pressure kneader and an open roll, and subjected to a crosslinking reaction in a press at 170°C for 20 minutes, followed by a crosslinking reaction in a gear oven at 170°C for 4 hours. This resulted in a cured product of the rubber composition. The tensile strength, elongation, and compression set of the cured product were measured using the methods described above. The results are shown in Table 1. In Table 1, the amount of each component is expressed in parts by mass, and the proportion of each component is expressed in mass percentage. The same applies to Tables 2 to 6.

[0060] Comparative Example 1 A rubber composition was prepared in the same manner as in Example 1, except that 75 parts by mass of carbon black (SRF) (product name: Seast S, manufactured by Tokai Carbon Co., Ltd.) was used as the filler instead of 50 parts by mass of silica, and a cured product was obtained and evaluated. The results are shown in Table 1.

[0061] Comparative Example 2 A rubber composition was prepared in the same manner as in Example 1, except that 1.1 parts by mass of an amino group-containing silane coupling agent (aminopropyltrimethoxysilane) was used instead of 2 parts by mass of polyorganosiloxane, and a cured product was obtained and evaluated. The results are shown in Table 1.

[0062] Comparative Example 3 A rubber composition was prepared in the same manner as in Example 1, except that 1.5 parts by mass of an epoxy group-containing silane coupling agent (glycidyloxypropyltrimethoxysilane) was used instead of 2 parts by mass of polyorganosiloxane, and a cured product was obtained and evaluated. The results are shown in Table 1.

[0063]

[0064] As shown in Table 1, Example 1 using the rubber composition according to the present embodiment had a higher tensile strength than Comparative Example 1 using carbon black as a conventional filler, and Comparative Examples 2 and 3 using an amino group- or epoxy group-containing silane coupling agent. The elongation was also high, and the compression set was comparable.

[0065] Example 2 A rubber composition was prepared in the same manner as in Example 1, except that the blending amount of polyorganosiloxane was changed to 1 part by mass, and a cured product was obtained and evaluated. The results are shown in Table 2.

[0066] Example 3 A rubber composition was prepared in the same manner as in Example 1, except that the blending amount of polyorganosiloxane was changed to 3 parts by mass, and a cured product was obtained and evaluated. The results are shown in Table 2.

[0067] Example 4 A rubber composition was prepared in the same manner as in Example 1, except that the blending amount of polyorganosiloxane was changed to 4 parts by mass, and a cured product was obtained and evaluated. The results are shown in Table 2.

[0068]

[0069] As shown in Table 2, even when the blending amount of polyorganosiloxane was changed, the cured product according to this embodiment exhibited high tensile strength. Furthermore, the elongation and compression set also showed values ​​sufficient for practical use.

[0070] [Example 5] A rubber composition was prepared in the same manner as in Example 1, except that the compounding amount of silica was changed to 40 parts by mass, the compounding amount of polyorganosiloxane was changed to 2.4 parts by mass, the compounding amount of vulcanizing agent was changed to 0.4 parts by mass, and the compounding amount of vulcanization accelerator was changed to 0.8 parts by mass, and then a cured product was obtained and evaluated. The results are shown in Table 3.

[0071] [Example 6] A rubber composition was prepared in the same manner as in Example 5, except that the amount of silica was changed to 50 parts by mass and the amount of polyorganosiloxane was changed to 3 parts by mass, and a cured product was obtained and evaluated. The results are shown in Table 3.

[0072] [Example 7] A rubber composition was prepared in the same manner as in Example 5, except that the compounded amount of silica was changed to 60 parts by mass and the compounded amount of polyorganosiloxane was changed to 3.6 parts by mass, and a cured product was obtained and evaluated. The results are shown in Table 3.

[0073]

[0074] As shown in Table 3, even when the amount of silica added was changed, the cured product according to this embodiment exhibited high tensile strength. Furthermore, the elongation and compression set also showed values ​​sufficient for practical use.

[0075] [Example 8] As silica, Nipsil ER (trade name, manufactured by Tosoh Silica Corporation, BET specific surface area: 100 m ２ / g), Nipsil ER (trade name, manufactured by Tosoh Silica Corporation, BET specific surface area: 130 m ２ A rubber composition was prepared in the same manner as in Example 3, except that a hydroxypropyl methylcellulose (H2SO4 / g) was used and the amount of polyorganosiloxane was changed to 4 parts by mass, and a cured product was obtained and evaluated. The results are shown in Table 4.

[0076]

[0077] As shown in Table 4, even when the specific surface area of ​​the silica was changed, the cured product according to this embodiment exhibited high tensile strength. Furthermore, the elongation and compression set also showed values ​​sufficient for practical use.

[0078] Example 9 A rubber composition was prepared by mixing the following components: Acrylic rubber: Denka ER 5300 (trade name, manufactured by Denka Co., Ltd.): 100 parts by mass Silica: Nipsil ER (trade name, manufactured by Tosoh Silica Corporation, BET specific surface area: 100 m ２ / g): 50 parts by mass Polyorganosiloxane: Struktol HT750 (trade name, manufactured by Struktol Co., Ltd.): 3 parts by mass Antiaging agent: DCD (Nauguard #445 manufactured by S.I. Group Co., Ltd.): 1 part by mass Lubricant: stearic acid: 1 part by mass Vulcanizing agent: CN-25 (trade name, manufactured by Shikoku Chemical Industries, Ltd., 1-cyanoethyl-2-methylimidazole masterbatch product) 1.4 parts by mass Vulcanization accelerator: ammonium benzoate: 0.3 parts by mass Vulcanization accelerator: sodium lauryl sulfate: 1 part by mass Note that Denka ER 5300 contains, as a polymer composition, 44 parts by mass of ethyl acrylate, 36 parts by mass of butyl acrylate, 14 parts by mass of vinyl acetate, 4 parts by mass of ethylene, and 1.6 parts by mass of an epoxy group-containing monomer.

[0079] Except for using the above rubber composition, a rubber composition was prepared in the same manner as in Example 1, and a cured product was obtained and evaluated. The results are shown in Table 5.

[0080] Comparative Example 4 A rubber composition was prepared in the same manner as in Example 9, except that silica and polyorganosiloxane were not blended and 75 parts by mass of carbon black (SRF) (product name: Seast S, manufactured by Tokai Carbon Co., Ltd.) was blended instead, and a cured product was obtained and evaluated. The results are shown in Table 5.

[0081] Example 10 A rubber composition was prepared by mixing the following components: Acrylic rubber: Acrylic rubber A: 100 parts by mass Silica: Nipsil ER (trade name, manufactured by Tosoh Silica Corporation, BET specific surface area: 100 m ２ / g): 50 parts by mass Polyorganosiloxane: Struktol HT750 (trade name, manufactured by Struktol): 3 parts by mass Antiaging agent: DCD (Nauguard #445 manufactured by S.I. Group Co., Ltd.): 1 part by mass Lubricant: stearic acid: 1 part by mass Lubricant: stearylamine: 0.3 parts by mass Vulcanizing agent: hexamethylenediamine carbamate: 0.4 parts by mass Vulcanization accelerator: Rhenogran XLA-60 (trade name, manufactured by Lanxess AG): 0.8 parts by mass The acrylic rubber A contains, as a polymer composition, 46 parts by mass of ethyl acrylate, 25 parts by mass of butyl acrylate, 28 parts by mass of butyl methacrylate, 1 part by mass of ethylene, and 1.5 parts by mass of a carboxyl group-containing monomer.

[0082] Except for using the above rubber composition, a rubber composition was prepared in the same manner as in Example 1, and a cured product was obtained and evaluated. The results are shown in Table 5.

[0083] Comparative Example 5 A rubber composition was prepared in the same manner as in Example 10, except that silica and polyorganosiloxane were not blended and 75 parts by mass of carbon black (SRF) (product name: Seast S, manufactured by Tokai Carbon Co., Ltd.) was blended instead, and a cured product was obtained and evaluated. The results are shown in Table 5.

[0084]

[0085] As shown in Table 5, even when the type of acrylic rubber was changed, the cured products according to the present embodiment in Examples 9 and 10 exhibited higher tensile strength and elongation than the cured products in Comparative Examples 4 and 5, respectively, and had equivalent compression set.

[0086] Example 11 A rubber composition was prepared by mixing the following components: Acrylic rubber: Nipol AR12 (trade name, manufactured by Zeon Corporation): 100 parts by mass Silica: Nipsil ER (trade name, manufactured by Tosoh Silica Corporation, BET specific surface area: 100 m ２ / g): 50 parts by mass Polyorganosiloxane: Struktol HT750 (trade name, manufactured by Struktol): 3 parts by mass Antiaging agent: DCD (Nauguard #445 manufactured by S.I. Group Co., Ltd.): 1 part by mass Lubricant: stearic acid: 1 part by mass Lubricant: stearylamine: 0.3 parts by mass Vulcanizing agent: hexamethylenediamine carbamate: 0.6 parts by mass Vulcanization accelerator: Rhenogran XLA-60 (trade name, manufactured by Lanxess AG): 2.0 parts by mass Nipol AR12 contains, as a polymer composition, 50 parts by mass of ethyl acrylate, 50 parts by mass of butyl acrylate, and 1.1 parts by mass of a carboxyl group-containing monomer.

[0087] Except for using the above rubber composition, a rubber composition was prepared in the same manner as in Example 1, and a cured product was obtained and evaluated. The results are shown in Table 6.

[0088] Comparative Example 6 A rubber composition was prepared in the same manner as in Example 11, except that silica and polyorganosiloxane were not blended and 60 parts by mass of carbon black (FEF) (product name: Seast SO, manufactured by Tokai Carbon Co., Ltd.) was blended instead, and a cured product was obtained and evaluated. The results are shown in Table 6.

[0089] Example 12 A rubber composition was prepared by mixing the following components: Acrylic rubber: Hytemp AR212XP (trade name, manufactured by Zeon Corporation): 100 parts by mass Silica: Nipsil ER (trade name, manufactured by Tosoh Silica Corporation, BET specific surface area: 100 m ２ / g): 50 parts by mass Polyorganosiloxane: Struktol HT750 (trade name, manufactured by Struktol): 2 parts by mass Antiaging agent: DCD (Nauguard #445 manufactured by S.I. Group Co., Ltd.): 1 part by mass Lubricant: stearic acid: 1 part by mass Lubricant: stearylamine: 0.3 parts by mass Vulcanizing agent: hexamethylenediamine carbamate: 0.6 parts by mass Vulcanization accelerator: Rhenogran XLA-60 (trade name, manufactured by Lanxess AG): 2.0 parts by mass Hytemp AR212XP contains, as a polymer composition, 65 parts by mass of ethyl acrylate, 34 parts by mass of butyl acrylate, and 0.5 parts by mass of a carboxyl group-containing monomer.

[0090] Except for using the above rubber composition, a rubber composition was prepared in the same manner as in Example 1, and a cured product was obtained and evaluated. The results are shown in Table 6.

[0091] Comparative Example 7 A rubber composition was prepared in the same manner as in Example 12, except that silica and polyorganosiloxane were not blended and 60 parts by mass of carbon black (FEF) (product name: Seast SO, manufactured by Tokai Carbon Co., Ltd.) was blended instead, and a cured product was obtained and evaluated. The results are shown in Table 6.

[0092] Example 13 A rubber composition was prepared by mixing the following components: Acrylic rubber: Racester CT (trade name, manufactured by Osaka Soda Co., Ltd.): 100 parts by mass Silica: Nipsil ER (trade name, manufactured by Tosoh Silica Corporation, BET specific surface area: 100 m ２ / g): 50 parts by mass Polyorganosiloxane: Struktol HT750 (trade name, manufactured by Struktol): 2 parts by mass Antiaging agent: DCD (Nauguard #445 manufactured by SI Group Co., Ltd.): 1 part by mass Lubricant: stearic acid: 1 part by mass Lubricant: stearylamine: 0.3 parts by mass Vulcanizing agent: hexamethylenediamine carbamate: 0.6 parts by mass Vulcanization accelerator: Rhenogran XLA-60 (trade name, manufactured by Lanxess AG): 2.0 parts by mass Racrester CT contains, as a polymer composition, 74 parts by mass of ethyl acrylate, 18 parts by mass of butyl acrylate, 8 parts by mass of butyl methacrylate, and 1.1 parts by mass of a carboxyl group-containing monomer.

[0093] Except for using the above rubber composition, a rubber composition was prepared in the same manner as in Example 1, and a cured product was obtained and evaluated. The results are shown in Table 6.

[0094] [Comparative Example 8] A rubber composition was prepared in the same manner as in Example 13, except that silica and polyorganosiloxane were not blended and 60 parts by mass of carbon black (FEF) (product name: Seast SO, manufactured by Tokai Carbon Co., Ltd.) was blended instead, and a cured product was obtained and evaluated. The results are shown in Table 6.

[0095]

[0096] As shown in Table 6, even when the type of acrylic rubber was changed, the cured products according to the present embodiment in Examples 11 to 13 exhibited higher tensile strength and elongation than the cured products in Comparative Examples 6 to 8, respectively, and had equivalent compression set.

Claims

1. an acrylic rubber which is a copolymer of a monomer containing an alkyl (meth)acrylate; Silica and a polyorganosiloxane having two or more amino groups per molecule; A rubber composition comprising:

2. 2. The rubber composition according to claim 1, wherein the acrylic rubber is a carboxyl group-containing acrylic rubber which is a copolymer of monomers including an alkyl (meth)acrylate and a carboxyl group-containing monomer.

3. 2. The rubber composition according to claim 1, wherein the acrylic rubber is a carboxyl group-containing acrylic rubber which is a copolymer of monomers including an alkyl (meth)acrylate, a carboxyl group-containing monomer, and an olefin.

4. The rubber composition according to claim 1, wherein the acrylic rubber is an epoxy group-containing acrylic rubber which is a copolymer of monomers including an alkyl (meth)acrylate and an epoxy group-containing monomer.

5. The rubber composition according to claim 4, wherein the acrylic rubber is an epoxy group-containing acrylic rubber which is a copolymer of monomers including an alkyl (meth)acrylate, an epoxy group-containing monomer, an olefin, and a vinyl carboxylate.

6. The rubber composition according to claim 3, wherein the olefin is at least one selected from the group consisting of ethylene, butadiene, and isoprene.

7. The BET specific surface area of ​​the silica is 100 to 130 m ２ The rubber composition according to claim 1, wherein the elastic modulus is 1 / g.

8. The rubber composition according to claim 1, wherein the alkyl moiety of the alkyl (meth)acrylate has 1 to 4 carbon atoms.

9. The rubber composition according to claim 1 , wherein the polyorganosiloxane has the following structural unit (I): [R １ ｘ R ａ SiO （４－（ｘ＋ａ））／２ ] (I) In formula (I), x is 1, 2 or 3, a is 0, 1 or 2, x+a<4, each R is independently methyl, ethyl, propyl, phenyl or hydroxy, and R １ are each independently NH ２ is a monovalent organic residue having a group.)

10. 2. The rubber composition according to claim 1, wherein a mass ratio of the silica to the acrylic rubber (silica / acrylic rubber) is 0.2 to 1.

0.

11. The rubber composition according to claim 1, wherein a mass ratio of the polyorganosiloxane to the acrylic rubber (polyorganosiloxane / acrylic rubber) is 0.005 to 0.

08.

12. The rubber composition according to claim 1, wherein a mass ratio of the polyorganosiloxane to the silica (polyorganosiloxane / silica) is 0.01 to 0.

3.

13. A cured product obtained by curing the rubber composition according to any one of claims 1 to 12.

14. A hose, seal, or gasket comprising the cured product of claim 13.