Carboxyl group-containing acrylic rubber composition and laminate

Abstract

The purpose of the present invention is to provide a multilayer body of a carboxyl group-containing acrylic rubber composition and a fluorine rubber composition, said multilayer body exhibiting sufficient adhesion, by thermally crosslinking and bonding the carboxyl group-containing acrylic rubber composition and the fluorine rubber composition. The present invention relates to a carboxyl group-containing acrylic rubber composition which contains (A) a carboxyl group-containing acrylic rubber, (B) a thiuram compound and / or a compound having an N-S bond, (C) a tertiary amine and / or a guanidine compound and (D) an aliphatic diamine compound and / or an aromatic diamine compound, and which has a scorching time t5 of 60 minutes or less at 125°C.

Description

[Technical Field]

[0001] The present invention relates to an acrylic rubber, a carboxyl group-containing acrylic rubber composition which is excellent in various physical properties such as normal physical properties, heat resistance, and oil resistance, and which can be directly crosslinked and bonded to a fluororubber without an adhesive layer, and a laminate thereof. [Background technology]

[0002] In recent years, regulations on exhaust gas emissions from automobiles have become increasingly strict, and the development of fuel hoses for use in automobiles and the like that combine heat aging resistance, weather resistance, resistance to rancid gasoline, resistance to alcohol-containing gasoline, and gasoline impermeability, etc., is underway. Furthermore, as part of efforts to reduce environmental impact, demand for diesel engines is increasing, particularly in Europe, and the characteristics of the turbochargers used in diesel engines require even higher heat aging resistance, etc. One such fuel hose material is fluorine-containing rubber, which has high performance in meeting the above requirements. However, it is expensive and suffers from poor cold resistance. Therefore, development is underway of laminates that use a thin layer of fluorine-containing rubber as an inner layer and another type of rubber as an outer layer.

[0003] Generally, in the case of a laminate made of fluororubber and other rubbers as described above, the adhesion between the rubbers is very important, but it is known that fluororubber has poor adhesion to other rubbers. There are three types of crosslinking methods for fluororubber: diamine crosslinking, polyol crosslinking, and peroxide crosslinking, and peroxide-crosslinked fluororubber has excellent performance in terms of chemical resistance, steam resistance, compression set, etc. (Non-Patent Document 1).

[0004] Patent Document 1 discloses that in a laminate of peroxide-crosslinkable fluororubber and acrylic rubber, an acrylic rubber obtained by adding 1,4-diazabicyclo[2.2.2]octane, a crosslinking agent for carboxyl-group-containing acrylic rubber, and a guanidine-based, thiuram-based, or thiourea-based crosslinking accelerator to a carboxyl-group-containing acrylic rubber can improve adhesion to the peroxide-crosslinkable fluororubber.

[0005] The peroxide-crosslinkable fluororubber used in Patent Document 1 contains magnesium oxide as a filler, and by compounding such a metal oxide, it is possible to obtain effects such as improved adhesion and adhesion in laminates of fluororubbers, fluororubber and other rubbers, or fluororubber and metals. In addition, when used in another crosslinking system, it also has the effect of acting as an acid acceptor.

[0006] However, there are concerns that poor dispersion of fillers during roll processing may result in a deterioration of normal physical properties, and that the filler components may dissolve in oil components such as gasoline, causing cracks and reducing oil and chemical resistance. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2018 / 110701 [Non-patent literature]

[0008] [Non-Patent Document 1] Tokuhira Katsusada, "Compounding of Fluorine Rubber," Journal of the Society of Rubber Science and Technology of Japan, Vol. 73, No. 6, 2000, pp. 298-306 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a laminate of a carboxyl group-containing acrylic rubber composition and a fluororubber composition having sufficient adhesiveness, which is obtained by thermally crosslinking and bonding a carboxyl group-containing acrylic rubber composition and a fluororubber composition. [Means for solving the problem]

[0010] The aspects of the present invention are as follows. Item 1: Contains (A) a carboxyl group-containing acrylic rubber, (B) a thiuram compound and / or a compound having an N-S bond, (C) a tertiary amine and / or a guanidine compound, and (D) an aliphatic diamine compound and / or an aromatic diamine compound, A carboxyl group-containing acrylic rubber composition having a scorch time t5 at 125°C of 60 minutes or less. Item 2. The carboxyl group-containing acrylic rubber composition according to Item 1, wherein the compound having an N-S bond (B) is 4,4'-dithiodimorpholine. Item 3. A carboxyl group-containing acrylic rubber composition according to item 1 or 2, wherein the content of component (B) is 0.1 to 10 parts by mass per 100 parts by mass of component (A). Item 4. The carboxyl group-containing acrylic rubber composition according to any one of Items 1 to 3, wherein the (C) tertiary amine and / or guanidine compound is at least one selected from the group consisting of 1,8-diazabicyclo(5.4.0)undecene-7 and salts thereof, and 1,3-di-o-tolylguanidine. Item 5. A carboxyl group-containing acrylic rubber composition according to any one of Items 1 to 4, wherein the content of the component (C) is 0.1 to 10 parts by mass per 100 parts by mass of the component (A). Item 6. The carboxyl group-containing acrylic rubber composition according to any one of Items 1 to 5, wherein the aliphatic diamine compound and / or aromatic diamine compound (D) is hexamethylenediamine carbamate and / or 2,2-bis[4-(4-aminophenoxy)phenyl]propane. Item 7. A carboxyl group-containing acrylic rubber composition according to any one of Items 1 to 6, wherein the content of the component (D) is 0.1 to 6 parts by mass per 100 parts by mass of the component (A). Item 8. A laminate obtained by laminating a cross-linked product of the carboxyl group-containing acrylic rubber composition according to any one of items 1 to 7 and a cross-linked product of a fluororubber composition. Item 9. A tube or hose made of the laminate according to item 8. Item 10. A fuel piping or air piping product comprising the tube or hose described in Item 9. [Effects of the Invention]

[0011] The carboxyl group-containing acrylic rubber composition of the present invention is excellent in various physical properties such as normal physical properties, heat resistance and oil resistance, and further, it is possible to provide a carboxyl group-containing acrylic rubber composition which can be directly crosslinked and bonded to a fluororubber composition without an adhesive layer, and a laminate thereof. DETAILED DESCRIPTION OF THE INVENTION

[0012] The carboxyl group-containing acrylic rubber composition of the present invention contains at least (A) a carboxyl group-containing acrylic rubber, (B) a thiuram compound and / or a compound having an N-S bond, (C) a tertiary amine and / or a guanidine compound, and (D) an aliphatic diamine compound and / or an aromatic diamine compound, and has a scorch time t5 of 60 minutes or less at a temperature of 125°C. Since the carboxyl group-containing acrylic rubber composition of the present invention contains (A), (B), (C), and (D) and has a scorch time t5 of 60 minutes or less at a temperature of 125°C, it exhibits excellent processability such as roll processability, excellent physical properties such as normal physical properties, heat resistance, and oil resistance, and further exhibits excellent adhesion to fluororubber compositions.

[0013] The reason why the above-mentioned effects are achieved is not entirely clear, but is presumed to be as follows. The (C) tertiary amine and / or guanidine compound is a component that acts as a crosslinking accelerator for the (A) carboxyl group-containing acrylic rubber in the carboxyl group-containing acrylic rubber composition of the present invention, and the (D) aliphatic diamine compound and / or aromatic diamine compound can easily form a crosslinked structure with carboxyl groups, and therefore, in the carboxyl group-containing acrylic rubber composition of the present invention, it is a component that acts as a crosslinking agent for the (A) carboxyl group-containing acrylic rubber. On the other hand, (B) the thiuram compound and / or compound having an N-S bond is a component that acts as an adhesive for the fluororubber composition. While the reason for the improved adhesion is not entirely clear, it is believed that the heat generated when crosslinking the carboxyl group-containing acrylic rubber composition of the present invention decomposes (B) the thiuram compound and / or compound having an N-S bond, and the resulting N-H groups react with fluorine at the interface with the fluororubber composition, abstracting HF groups. As a result, the fluororubber composition becomes more susceptible to reaction with the acrylic rubber composition, thereby improving adhesion. By simultaneously using specific components (A), (C), and (D), a carboxyl group-containing acrylic rubber composition having an appropriate crosslink density can be obtained. By further blending this carboxyl group-containing acrylic rubber composition with component (B), which acts as an adhesive, the composition has excellent processability, such as roll processability, and excellent physical properties, such as normal physical properties, heat resistance, and oil resistance, and has strong adhesion to fluororubber. Furthermore, since such a carboxyl group-containing acrylic rubber composition has a scorch time t5 of 60 minutes or less at a temperature of 125°C, it is highly reactive and is in a state where it easily reacts with the fluororubber composition, and it is presumed that the above-mentioned effects can be more significantly obtained.

[0014] The (A) carboxyl group-containing acrylic rubber used in the present invention includes an acrylic rubber containing (A-1) 10 to 98.9 mass% of structural units derived from a (meth)acrylic acid ester having an alkyl group with 1 to 3 carbon atoms or an alkoxyalkyl group with 2 to 3 carbon atoms, (A-2) 0 to 88.9 mass% of structural units derived from a (meth)acrylic acid ester having an alkyl group with 4 to 8 carbon atoms or an alkoxyalkyl group with 4 to 8 carbon atoms, and (A-3) 0.1 to 5 mass% of structural units derived from an ethylenically unsaturated carboxylic acid. The (A) carboxyl group-containing acrylic rubber may be used alone or in combination with two or more types. The term "(meth)acrylic acid ester" means "acrylic acid ester or methacrylic acid ester," and the same applies to similar expressions in the present application.

[0015] Specific examples of (A-1) (meth)acrylic acid esters having an alkyl group having 1 to 3 carbon atoms or an alkoxyalkyl group having 2 to 3 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, and ethoxymethyl (meth)acrylate. These can be used alone or in combination of two or more. Among these, ethyl (meth)acrylate and methoxyethyl (meth)acrylate are particularly preferred.

[0016] The content of the structural unit (A-1) in the carboxyl group-containing acrylic rubber (A) is 10 to 98.9 mass% of all structural units, preferably 15 to 98 mass%, and more preferably 20 to 97.5 mass%. If the content of the structural unit (A-1) is too low, the acrylic rubber will have increased tackiness, particularly when made into a crosslinkable rubber composition, resulting in reduced roll processability. On the other hand, if the content is too high, the cold resistance will be reduced.

[0017] Specific examples of (A-2) (meth)acrylic acid esters having an alkyl group having 4 to 8 carbon atoms or an alkoxyalkyl group having 4 to 8 carbon atoms include n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-methoxypropyl (meth)acrylate, 2-ethoxypropyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate, etc. These may be used alone or in combination of two or more. Among these, n-butyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate are particularly preferred.

[0018] The content of the structural unit (A-2) in the carboxyl group-containing acrylic rubber (A) is 0 to 88.9% by mass, preferably 0 to 75% by mass, and more preferably 0 to 65% by mass, of all structural units. If the content of the structural unit (A-2) is too high, roll processability will decrease.

[0019] Examples of (A-3) ethylenically unsaturated carboxylic acids include ethylenically unsaturated monocarboxylic acids having 3 to 12 carbon atoms, ethylenically unsaturated dicarboxylic acids having 4 to 12 carbon atoms, and monoalkyl esters of ethylenically unsaturated dicarboxylic acids having 4 to 12 carbon atoms with alkanols having 1 to 8 carbon atoms (sometimes referred to as ethylenically unsaturated dicarboxylic acid monoesters).

[0020] Specific examples of the ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms include acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, and cinnamic acid.

[0021] Specific examples of the ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms include fumaric acid, maleic acid, citraconic acid, mesaconic acid, itaconic acid, 2-pentenedioic acid, acetylenedicarboxylic acid, and anhydrides thereof.

[0022] Specific examples of the ethylenically unsaturated dicarboxylic acid monoester having 4 to 12 carbon atoms include monomethyl fumarate, monoethyl fumarate, monopropyl fumarate, mono-n-butyl fumarate, monoisobutyl fumarate, monocyclohexyl fumarate, monomethyl maleate, monoethyl maleate, monopropyl maleate, mono-n-butyl maleate, monomethyl citraconic acid, monoethyl citraconic acid, monopropyl citraconic acid, mono-n-butyl citraconic acid, monomethyl mesaconic acid, monoethyl mesaconic acid, and monomethyl ... monopropyl ester, mono-n-butyl mesaconic acid, monomethyl itaconate, monoethyl itaconate, mono-n-butyl itaconate, monocyclohexyl itaconate, monomethyl 2-pentenedioate, monoethyl 2-pentenedioate, monopropyl 2-pentenedioate, mono-n-butyl 2-pentenedioate, monomethyl acetylenedicarboxylate, monoethyl acetylenedicarboxylate, monopropyl acetylenedicarboxylate, mono-n-butyl acetylenedicarboxylate, and monocyclohexyl acetylenedicarboxylate.

[0023] These (A-3) ethylenically unsaturated carboxylic acids can be used alone or in combination of two or more. Among these, monoethyl fumarate, monopropyl fumarate, mono-n-butyl fumarate, monoisobutyl fumarate, monomethyl itaconate, and mono-n-butyl itaconate are preferred.

[0024] The content of the structural unit (A-3) in the carboxyl group-containing acrylic rubber (A) is 0.1 to 5 mass% of all structural units, preferably 0.2 to 4 mass%, and more preferably 0.5 to 3 mass%. If the content of the structural unit (A-3) is too low, the effectiveness of the structural unit (A-3) may not be fully obtained, the cross-linking density of the obtained cross-linked rubber product may not be sufficient, and good cross-linking properties may not be obtained. On the other hand, if the content is too high, the elongation of the obtained cross-linked rubber product may decrease.

[0025] As long as the properties of acrylic rubber are maintained, the (A) carboxyl group-containing acrylic rubber may have structural units derived from other copolymerizable monomers in addition to the structural units (A-1) to (A-3) derived from the (meth)acrylic acid ester or ethylenically unsaturated carboxylic acid described above.

[0026] The copolymerizable other monomer is not particularly limited, but examples thereof include aromatic vinyl monomers, ethylenically unsaturated nitrile monomers, conjugated diene monomers, olefin monomers, and vinyl ether compounds.

[0027] Specific examples of aromatic vinyl monomers include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, α-fluorostyrene, p-trifluoromethylstyrene, p-methoxystyrene, p-aminostyrene, p-dimethylaminostyrene, p-acetoxystyrene, styrenesulfonic acid or a salt thereof, α-vinylnaphthalene, 1-vinylnaphthalene-4-sulfonic acid or a salt thereof, 2-vinylfluorene, 2-vinylpyridine, 4-vinylpyridine, divinylbenzene, diisopropenylbenzene, and vinylbenzyl chloride.

[0028] Specific examples of the ethylenically unsaturated nitrile monomer include acrylonitrile, methacrylonitrile, α-methoxyacrylonitrile, and vinylidene cyanide.

[0029] Specific examples of conjugated diene monomers include 1,3-butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene (chloroprene), 1,2-dichloro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-neopentyl-1,3-butadiene, 2-bromo-1,3-butadiene, 2-cyano-1,3-butadiene, 1,3-pentadiene (piperylene), and 1,3-hexadiene.

[0030] Specific examples of olefin-based monomers include ethylene, propylene, vinyl chloride, vinylidene chloride, 1,2-dichloroethylene, vinyl acetate, vinyl fluoride, vinylidene fluoride, 1,2-difluoroethylene, vinyl bromide, vinylidene bromide, and 1,2-dibromoethylene.

[0031] Specific examples of the vinyl ether compound include ethyl vinyl ether, dimethylaminoethyl vinyl ether, and n-butyl vinyl ether.

[0032] Other examples include non-conjugated dienes such as 1,4-pentadiene, 1,4-hexadiene, ethylidenenorbornene, norbornadiene, and dicyclopentadiene; and esters such as dicyclopentadienyl acrylate, dicyclopentadienyl methacrylate, dicyclopentadienylethyl acrylate, dicyclopentadienylethyl methacrylate, and vinyl acetate.

[0033] The copolymerizable other monomers may be used alone or in combination of two or more. The content of structural units derived from copolymerizable other monomers in the (A) carboxyl group-containing acrylic rubber is 0 to 45% by mass, and preferably 0 to 20% by mass, of all structural units.

[0034] The carboxyl group-containing acrylic rubber (A) used in the present invention can be obtained by copolymerizing the above-mentioned monomers. The polymerization reaction can be carried out by any of emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization, but from the viewpoint of ease of control of the polymerization reaction, emulsion polymerization under normal pressure, which is commonly used as a conventional method for producing acrylic rubber, is preferred.

[0035] The emulsion polymerization method may be any of a batch method, a semi-batch method, and a continuous method. The polymerization temperature is usually 0 to 70°C, and preferably 5 to 50°C.

[0036] The glass transition temperature (Tg) of the carboxyl group-containing acrylic rubber (A) used in the present invention, thus produced, is preferably −70° C. to −5° C., more preferably −60° C. to −10° C., and even more preferably −50° C. to −20° C. The Mooney viscosity (ML1+4, 100° C.) (polymer Mooney) of the carboxyl group-containing acrylic rubber (A) is preferably 10 to 80, more preferably 20 to 70, and even more preferably 25 to 60. In this specification, the glass transition temperature (Tg) of the carboxyl group-containing acrylic rubber (A) is determined according to JIS K6240, and the Mooney viscosity (ML1+4, 100° C.) is determined according to JIS K6300.

[0037] The carboxyl group-containing acrylic rubber composition of the present invention contains at least (A) a carboxyl group-containing acrylic rubber, (B) a thiuram compound and / or a compound having an N-S bond, (C) a tertiary amine and / or a guanidine compound, and (D) an aliphatic diamine compound and / or an aromatic diamine compound.

[0038] (B) The thiuram compound and / or the compound having an N-S bond is a component that acts as an adhesive for the fluororubber composition. The reason for the improved adhesion is not entirely clear, but it is presumed that the heat generated when crosslinking the carboxyl group-containing acrylic rubber composition of the present invention decomposes (B) the thiuram compound and / or the compound having an N-S bond, and the resulting N-H groups react with fluorine at the interface with the fluororubber composition to abstract HF groups, thereby improving adhesion.

[0039] Specific examples of the thiuram compound (B) used in the present invention include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetra-n-butylthiuram disulfide, dipentamethylene thiuram tetrasulfide, etc. Among these, from the viewpoint of adhesion to the fluororubber composition, tetramethylthiuram disulfide, tetraethylthiuram disulfide and dipentamethylene thiuram tetrasulfide are preferred, with dipentamethylene thiuram tetrasulfide being more preferred.

[0040] Specific examples of the compound (B) having an NS bond used in the present invention include N-cyclohexyl-2-benzothiazole sulfenamide, N-(tert-butyl)-2-benzothiazole sulfenamide, 2-morpholinothiobenzothiazole, 2-morpholinodithiobenzothiazole, 4,4'-dithiodimorpholine, etc. Among these, 4,4'-dithiodimorpholine is preferred from the viewpoint of adhesion to the fluororubber composition.

[0041] (B) The thiuram compound and / or compound having an N-S bond is preferably at least one selected from the group consisting of tetramethylthiuram disulfide, tetraethylthiuram disulfide, dipentamethylene thiuram tetrasulfide, and 4,4'-dithiodimorpholine, and more preferably dipentamethylene thiuram tetrasulfide.

[0042] In the present invention, (B) thiuram compounds and / or compounds having an N-S bond, which also fall under the category of (C) tertiary amine and / or guanidine compounds and (D) aliphatic diamine compounds and / or aromatic diamine compounds, as described below, are treated as component (B).

[0043] The (B) thiuram compound and / or compound having an NS bond may be used alone or in combination of two or more. The content of the (B) thiuram compound and / or compound having an NS bond is preferably 0.1 to 10 parts by mass, more preferably 0.15 to 8 parts by mass, and even more preferably 0.2 to 7 parts by mass, per 100 parts by mass of the (A) carboxyl group-containing acrylic rubber. If the content of the (B) thiuram compound and / or compound having an NS bond is too low, sufficient efficacy may not be obtained, and good crosslinking properties and adhesiveness may not be obtained. On the other hand, if the content is too high, poor dispersion and crosslinking inhibition may occur during roll processing. Furthermore, the crosslinking accelerator may bloom from the resulting crosslinked rubber, adversely affecting the appearance. When a plurality of components (B) are contained, the above content refers to the total content. The same applies to the contents of other components.

[0044] The tertiary amine and / or guanidine compound (C) is a component that acts as a crosslinking accelerator for the carboxyl group-containing acrylic rubber (A) in the carboxyl group-containing acrylic rubber composition of the present invention.

[0045] Specific examples of the (C) tertiary amine include aliphatic tertiary amines, dithiocarbamates, diazabicycloalkene compounds, etc. Among these, diazabicycloalkene compounds are preferred from the viewpoints of normal physical properties and heat resistance.

[0046] Specific examples of aliphatic tertiary amines include trimethylamine, triethylamine, tripropylamine, triallylamine, triisopropylamine, tri-n-butylamine, tri-t-butylamine, tri-sec-butylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, triundecylamine, and tridodecylamine.

[0047] Specific examples of dithiocarbamate salts include zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc dipentyldithiocarbamate, zinc dihexyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc dibenzyldithiocarbamate, copper dipropyldithiocarbamate, copper diisopropyldithiocarbamate, copper dibutyldithiocarbamate, sodium diethyldithiocarbamate, sodium diisopropyldithiocarbamate, sodium dibutyldithiocarbamate, ferric dimethyldithiocarbamate, and ferric diethyldithiocarbamate.

[0048] Specific examples of diazabicycloalkene compounds include 1,8-diazabicyclo(5.4.0)undecene-7 (DBU), 1,5-diazabicyclo(4.3.0)nonene-5, 1,4-diazabicyclo(2.2.2)octane, and their p-toluenesulfonate salts, phenol salts, phenol resin salts, orthophthalate salts, formate salts, octylate salts, naphthoate salts, etc. Among these, from the viewpoints of normal state physical properties and heat resistance, 1,8-diazabicyclo(5.4.0)undecene-7 and naphthoate salts of 1,8-diazabicyclo(5.4.0)undecene-7 are preferred.

[0049] Specific examples of the guanidine compound (C) include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc. Among these, 1,3-di-o-tolylguanidine is preferred from the viewpoints of normal state physical properties, heat resistance, and compression set.

[0050] Among these compounds, from the viewpoint of improving adhesiveness, at least one selected from the group consisting of 1,8-diazabicyclo(5.4.0)undecene-7, its salts, and 1,3-di-o-tolylguanidine is preferred, with 1,8-diazabicyclo(5.4.0)undecene-7 being more preferred. Furthermore, among the salts of 1,8-diazabicyclo(5.4.0)undecene-7, naphthoate is preferred.

[0051] In the present invention, (C) a tertiary amine and / or guanidine compound that also corresponds to (D) an aliphatic diamine compound and / or an aromatic diamine compound described below is treated as component (C).

[0052] The (C) tertiary amine and / or guanidine compound may be used alone or in combination of two or more. The content of the (C) tertiary amine and / or guanidine compound is preferably 0.1 to 10 parts by mass, more preferably 0.15 to 8 parts by mass, and even more preferably 0.2 to 7 parts by mass, per 100 parts by mass of the (A) carboxyl group-containing acrylic rubber.

[0053] Since (D) an aliphatic diamine compound and / or an aromatic diamine compound can easily form a crosslinked structure with a carboxyl group, it is a component that acts as a crosslinking agent for (A) the carboxyl group-containing acrylic rubber in the carboxyl group-containing acrylic rubber composition of the present invention. As (D), an aliphatic diamine compound is preferred.

[0054] Specific examples of the (D) aliphatic diamine compound include hexamethylenediamine, hexamethylenediamine carbamate, ethylenediamine, ethylenediamine carbamate, 3,3′-diaminopropylamine, diamino-modified siloxane, etc. Among these, hexamethylenediamine carbamate is preferred from the viewpoints of normal physical properties and heat resistance.

[0055] Specific examples of the aromatic diamine compound (D) include 4,4'-methylenedianiline, m-phenylenediamine, p-phenylenediamine, p,p'-ethylenedianiline, 4,4'-methylenebis(o-chloroaniline), 4,4'-(m-phenylenediisopropylidene)dianiline, 4,4'-(p-phenylenediisopropylidene)dianiline, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, bis[4-(4-aminophenoxy)phenyl]ether, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane ...3,4'-diaminodiphenyl ether, bis[4-(4-aminophenoxy)phenyl]propane, 3,4'-diaminodiphenyl ether, bis[4-(4-aminophenoxy)phenyl]propane, 3,4'-diaminodiphenyl ether, bis[4-(4-aminophenoxy)phenyl]propane, 3,4'-diaminodiphenyl ether, bis[4-(4-aminophenoxy)phenyl]propane, 3,4'- Examples of such an additive include aminobenzanilide, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, m-xylylenediamine, p-xylylenediamine, 4,4'-diaminodiphenyl sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, hexamethylenediamine-cinnamaldehyde adduct, hexamethylenediamine-dibenzoate salt, and N,N'-dicinnamylidene-1,6-hexanediamine. Among these, 2,2-bis[4-(4-aminophenoxy)phenyl]propane is preferred from the viewpoints of normal physical properties and heat resistance.

[0056] As the (D) aliphatic diamine compound and / or aromatic diamine compound, hexamethylenediamine carbamate and / or 2,2'-bis[4-(4-aminophenoxy)phenyl]propane are preferred, and hexamethylenediamine carbamate is more preferred. The (D) aliphatic diamine compound and / or aromatic diamine compound may be used alone or in combination of two or more. The content of the (D) aliphatic diamine compound and / or aromatic diamine compound is preferably 0.1 to 6 parts by mass, more preferably 0.15 to 5 parts by mass, and even more preferably 0.2 to 4 parts by mass, per 100 parts by mass of the (A) carboxyl group-containing acrylic rubber.

[0057] Furthermore, the carboxyl group-containing acrylic rubber composition of the present invention can be blended with various additives, such as fillers, processing aids, plasticizers, acid acceptors, softeners, antioxidants, colorants, stabilizers, adhesion aids, release agents, electrical conductivity imparting agents, thermal conductivity imparting agents, surface anti-tack agents, tackifiers, flexibility imparting agents, heat resistance improvers, flame retardants, ultraviolet absorbers, oil resistance improvers, foaming agents, scorch inhibitors, lubricants, etc., as long as the effects of the present invention are not impaired. These may be used alone or in combination of two or more.

[0058] As the filler, known fillers can be used, and specific examples include calcium carbonate, talc, silica, clay, carbon fiber, glass fiber, carbon black, titanium oxide, magnesium oxide, hydrotalcite, magnesium hydroxide, antimony oxide, zinc oxide, etc. Among these, carbon black and silica are preferred, and carbon black is more preferred. When carbon black is contained, its nitrogen adsorption specific surface area (N2SA) should be 15 to 90 m from the viewpoint of adhesion to the fluororubber composition. 2 / g is preferred, and 30 to 85m 2 / g is more preferable, and 35 to 60m 2 / g is more preferable. From the viewpoint of adhesion to the fluororubber composition, the average particle size is preferably 15 to 80 nm, more preferably 25 to 60 nm, and even more preferably 30 to 50 nm. When a filler is contained, the content thereof is preferably 1 to 150 parts by mass, and more preferably 10 to 100 parts by mass, per 100 parts by mass of (A) carboxyl group-containing acrylic rubber. In this specification, the nitrogen adsorption specific surface area of ​​carbon black is determined in accordance with JIS K6217-2:2001, and the average particle size is determined using a transmission electron microscope or the like.

[0059] 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 stearamide and oleamide; 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, phthalates, phosphates, rosin, (halogenated) dialkylamines, (halogenated) dialkylsulfones, surfactants, etc. When a processing aid is contained, the content thereof is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of (A) the carboxyl group-containing acrylic rubber.

[0060] Examples of the plasticizer include phthalic acid derivatives such as dioctyl phthalate (bis(2-ethylhexyl) phthalate) and diallyl phthalate ester, adipic acid derivatives such as dibutyl diglycol adipate and di(butoxyethoxy)ethyl adipate, sebacic acid derivatives such as dioctyl sebacate, and trimellitic acid derivatives such as trioctyl trimellitate, and these may be used alone or in combination of two or more.

[0061] Examples of the antioxidant include amines, phosphates, quinolines, cresols, phenols, and dithiocarbamate metal salts, and preferred are amines such as diphenylamine derivatives such as 4,4'-bis(α,α-dimethylbenzyl)diphenylamine and phenylenediamine derivatives. When an antioxidant is contained, the content thereof is preferably 0.3 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the (A) carboxyl group-containing acrylic rubber.

[0062] The carboxyl group-containing acrylic rubber composition of the present invention can be compounded using any means conventionally used in the field of polymer processing, such as an open roll, a Banbury mixer, or various kneaders.

[0063] The compounding procedure can be a normal procedure used in the field of polymer processing, for example, by first kneading only the polymer, then adding compounding ingredients other than the crosslinking agent and crosslinking accelerator to prepare kneaded compound A, and then kneading compound B to add the crosslinking agent and crosslinking accelerator.

[0064] The carboxyl group-containing acrylic rubber composition of the present invention obtained in this manner exhibits excellent roll processability during processing. When the carboxyl group-containing acrylic rubber composition of the present invention is formed into a sheet (uncrosslinked sheet) with a thickness of approximately 2 to 2.5 mm, the scorch time t5 (JIS K6300) at a temperature of 125°C is 60 minutes or less, preferably 0.5 to 60 minutes, more preferably 1 to 60 minutes, and even more preferably 2 to 55 minutes. If the scorch time t5 is too long, the crosslinking rate will be slow, and complete crosslinking will take a long time, which may prevent good crosslinked physical properties and adhesiveness from being obtained. The scorch time t5 can be adjusted to a desired value by adjusting the type and content of the crosslinking agent and crosslinking accelerator.

[0065] The carboxyl group-containing acrylic rubber composition of the present invention can be made into a carboxyl group-containing acrylic rubber cross-linked product by heating it usually at 100 to 250° C. The cross-linking time varies depending on the temperature, but is usually 0.5 to 300 minutes.

[0066] A general crosslinking molding method may be any of a method of integrally carrying out crosslinking and molding, a method of heating a previously molded crosslinkable acrylic rubber composition again to form a crosslinked product, and a method of processing an acrylic rubber crosslinked product that has been previously heated for molding. Specific methods for crosslinking molding include compression molding using a mold, injection molding, heating using a steam can, an air bath, infrared rays, or microwaves, and any other method can be used.

[0067] The carboxyl group-containing acrylic rubber cross-linked product thus obtained is obtained using the carboxyl group-containing acrylic rubber composition of the present invention, and therefore has excellent roll processability during processing, and when cross-linked, has excellent normal physical properties, heat resistance and oil resistance.

[0068] The laminate of the present invention is a laminate of a cross-linked product of the carboxyl group-containing acrylic rubber composition of the present invention and a cross-linked product of the fluororubber composition. The carboxyl group-containing acrylic rubber composition of the present invention and its cross-linked product are as described above. The fluororubber composition will be described below.

[0069] The fluororubber in the fluororubber composition is preferably a highly fluorinated elastic copolymer, such as a copolymer of vinylidene fluoride and another copolymerizable fluorine-containing olefin. Specific examples of the fluorine-containing olefin include hexafluoropropene, pentafluoropropene, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, vinyl fluoride, perfluoromethyl vinyl ether, and perfluoropropyl vinyl ether, and one or more of these are used as copolymerization components.

[0070] The crosslinking of the above-mentioned fluororubber may be carried out by any of diamine crosslinking, polyol crosslinking and peroxide crosslinking, and in consideration of the effects of the present invention, it is preferable to carry out the crosslinking by peroxide.

[0071] When peroxide crosslinking is performed, a peroxide crosslinking vulcanizing agent is blended into the fluororubber composition. Specific examples of the peroxide crosslinking vulcanizing agent include tert-butyl hydroperoxide, p-menthane hydroperoxide, dicumyl peroxide, tert-butyl peroxide, 1,3-bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, benzoyl peroxide, and tert-butyl peroxybenzoate.

[0072] The content of the peroxide crosslinking vulcanizing agent is determined appropriately depending on the purpose of use, but is preferably 0.1 to 5 parts by mass, and more preferably 0.2 to 4 parts by mass, relative to 100 parts by mass of the fluororubber. If the content is less than 0.1 part by mass, crosslinking will be insufficient, while if it exceeds 5 parts by mass, the crosslinked product will be too rigid, and there is a risk that the physical properties normally expected of a crosslinked fluororubber product will not be obtained.

[0073] The fluororubber composition used in the laminate of the present invention can be blended with various known compounding agents commonly used in the rubber processing field in addition to the peroxide crosslinking vulcanizing agent. Examples of such compounding agents include vulcanization accelerators, metal compounds that serve as acid acceptors, light stabilizers, fillers, colorants, processing aids, plasticizers, slip agents, adhesives, lubricants, flame retardants, mildew inhibitors, antistatic agents, colorants, silane coupling agents, crosslinking aids, and crosslinking retarders. The amounts of these compounding agents are not particularly limited as long as they do not impair the purpose and effects of the present invention, and can be appropriately blended in amounts depending on the purpose of blending.

[0074] Fillers are divided into two types: adhesion improvers for acrylic rubber compositions, such as the magnesium oxide used in Patent Document 1 mentioned above, and reinforcing agents. Specific examples of adhesion improvers include magnesium oxide, as well as oxides of monovalent or divalent metals (alkali metals or alkaline earth metals), and monovalent or divalent metal salts. More specific examples of adhesion improvers include metal oxides such as magnesium oxide, zinc oxide, calcium oxide, titanium oxide, and aluminum oxide. Specific examples of reinforcing agents include inorganic fillers such as carbon black and silica. These fillers may be used alone or in combination of two or more.

[0075] As described above, in Patent Document 1, the adhesiveness and adhesion of the laminate are improved by blending magnesium oxide as a filler into the peroxide-crosslinkable fluororubber, but the laminate of the present invention is formed by laminating a crosslinked product of the carboxyl group-containing acrylic rubber composition of the present invention, which has excellent adhesion to the fluororubber composition, with a crosslinked product of the fluororubber composition, and therefore has good adhesiveness even when the fluororubber composition does not contain an adhesion improver such as magnesium oxide. Therefore, it is preferable that the fluororubber composition does not contain an adhesion improver such as magnesium oxide.

[0076] In the fluororubber composition, the content of magnesium oxide (preferably metal oxide, more preferably adhesion improver) per 100 parts by mass of fluororubber is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 6 parts by mass or less, particularly preferably 3 parts by mass or less, even more preferably 1 part by mass or less, and most preferably 0 part by mass. This tends to result in a laminate with excellent adhesion.

[0077] Specific examples of the crosslinking aid include triallyl isocyanurate, diallyl phthalate, phenylenedimaleimide, benzoylquinone dioxime, trimethylolpropane trimethacrylate, etc. These crosslinking aids may be used alone or in combination of two or more.

[0078] As a method for compounding the fluororubber composition, any means conventionally used in the field of polymer processing, such as an open roll, a Banbury mixer, or various kneaders, can be used.

[0079] The compounding procedure can be a normal procedure used in the field of polymer processing, for example, by first kneading only the polymer, then adding compounding ingredients other than the crosslinking agent and crosslinking accelerator to prepare kneaded compound A, and then kneading compound B to add the crosslinking agent and crosslinking accelerator.

[0080] A crosslinked product of a fluororubber composition is usually obtained by heating the fluororubber composition to 100 to 200°C, and the crosslinking time varies depending on the temperature, but is usually 0.5 to 300 minutes. As a method for crosslinking molding, any method can be used, such as compression molding using a mold, injection molding, air bath, or infrared or microwave heating.

[0081] The laminate of the present invention preferably has a cross-linked product of a fluororubber composition in the inner layer and a cross-linked product of a carboxyl group-containing acrylic rubber composition of the present invention in the outer layer, as this provides excellent physical properties. In order to make the most of the advantage of the carboxyl group-containing acrylic rubber composition of the present invention having good adhesion to the fluororubber composition, it is preferred that the cross-linked product of the fluororubber composition in the inner layer and the cross-linked product of the carboxyl group-containing acrylic rubber composition of the present invention in the outer layer are in contact at least in part.

[0082] The laminate of the present invention, in which a cross-linked product of a carboxyl group-containing acrylic rubber composition and a cross-linked product of a fluororubber composition are laminated, achieves strong chemical adhesion during cross-linking without the need for particularly complicated processes, and therefore maintains sufficient adhesive strength even when exposed to harsh conditions (e.g., immersion in fuel oil). Furthermore, it can be easily molded at low cost and has good moldability. Furthermore, because it can be molded by a common method such as extrusion molding, it can be made thin and has excellent flexibility.

[0083] The laminate of the present invention is suitably used for fuel piping or air piping products such as tubes and hoses. [Example]

[0084] The present invention will be described in more detail below with reference to examples, but the following examples are not intended to limit the scope of the invention. Tests and evaluations of physical properties and characteristics were carried out as follows.

[0085] (Scorch Time t5) The carboxyl group-containing acrylic rubber composition was kneaded using a kneader and an open roll to prepare an uncrosslinked rubber sheet having a thickness of 2 to 2.5 mm. The scorch time t5 (the time from the start of measurement until the Mooney viscosity increases by 5 points compared to the minimum Mooney viscosity) was measured at 125°C using a Mooney Viscometer AM-3 manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K6300. If the scorch time t5 is 60 minutes or less, good crosslinking properties and adhesiveness can be obtained. On the other hand, if the scorch time t5 is longer than 60 minutes, it takes too long for complete crosslinking, and good crosslinking properties and adhesiveness may not be obtained.

[0086] (Normal physical properties: tensile strength, elongation) An uncrosslinked rubber sheet of the carboxyl group-containing acrylic rubber composition was pressed at 180°C for 10 minutes, and then heated in an air oven at 180°C for 3 hours to cause secondary crosslinking, thereby obtaining a carboxyl group-containing crosslinked acrylic rubber. Using the obtained carboxyl group-containing crosslinked acrylic rubber, the tensile strength (hereinafter also referred to as TB) and elongation (hereinafter also referred to as EB) were measured in accordance with JIS K6251.

[0087] (Normal physical properties: hardness) Using the carboxyl group-containing acrylic rubber cross-linked product, the type A durometer hardness (hereinafter also referred to as HS) was measured based on JIS K6253.

[0088] (Heat resistance test) Using a carboxyl group-containing cross-linked acrylic rubber, a heat resistance test was conducted at 175°C for 168 hours, after which the tensile strength, elongation, and hardness were measured in the same manner as in the normal physical property test. From the measurement results obtained, the rate of change (ΔTB, ΔEB, unit: %) of tensile strength and elongation before and after the test was calculated. In addition, the difference in hardness before and after the test (ΔHS, unit: pts) was calculated. The formulas for calculating the rate of change and difference are as follows. The smaller the rate of change and difference, the better the heat resistance. ΔTB = ((tensile strength after test - tensile strength before test) / tensile strength before test) × 100 ΔEB = ((elongation after test - elongation before test) / elongation before test) × 100 ΔHS = hardness after test - hardness before test

[0089] (Oil resistance test) A carboxyl group-containing cross-linked acrylic rubber was heated at 150°C for 72 hours in accordance with JIS K6258. The test liquid used was the No. 3 lubricating oil (product name "IRM903" manufactured by Nippon Sun Oil Co., Ltd.) specified in JIS K6258. After the test, the test specimen was removed, the test liquid was wiped off, and the tensile strength, elongation, and hardness were measured in the same manner as in the normal physical property test. From the obtained measurement results, the change rates of tensile strength and elongation before and after the test (ΔTB, ΔEB) and the difference in hardness before and after the test (ΔHS) were calculated in the same manner as in the heat resistance test. In addition, the volume and weight of the test specimen were measured in the oil resistance test, and the volume change rate ΔV (%) and weight change rate ΔW (%) were also calculated. The formulas for ΔV and ΔW are as follows: A smaller change rate of ΔV and ΔW indicates better oil resistance. ΔV = ((Volume after test - Volume before test) / Volume before test) x 100 ΔW = ((weight after test - weight before test) / weight before test) x 100

[0090] (Preparation of Fluororubber Composition) 100 parts by mass of peroxide-crosslinkable fluororubber (Dai-el G-8002, manufactured by Daikin Industries, Ltd.), 20 parts by mass of carbon black N990, and 4 parts by mass of triallyl isocyanurate were kneaded using a kneader. Further, 1.5 parts by mass of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (Perhexa 25B, manufactured by NOF Corporation) was added, and the mixture was kneaded using an open roll to prepare a fluororubber composition.

[0091] (Manufacturing of laminates) An uncrosslinked rubber sheet of a carboxyl group-containing acrylic rubber composition having a thickness of 2 to 2.5 mm and an uncrosslinked rubber sheet of a fluororubber composition having a thickness of 1.5 to 2 mm were prepared, and the uncrosslinked rubber sheets were laminated together and subjected to a temperature of 170°C and 25 to 30 kg / cm. 2 A laminate was obtained by performing primary crosslinking under pressure at 180° C. for 20 minutes, and then secondary crosslinking for 3 hours in an air oven at 180° C. The thickness of the obtained laminate was 3.5 to 4.5 mm.

[0092] (peel test) The laminate obtained above was cut into 1.0 x 8.0 cm strips to prepare test specimens for adhesion tests. Using an Autograph AGS-X manufactured by Shimadzu Corporation, the specimens were peeled at a tensile speed of 50 mm / min at 25°C, and the average peel strength obtained from 0 to 80 mm was calculated. If the material broke during the measurement, the measurement was stopped at that point, and the average peel strength obtained up to that point was calculated. Each test was performed three times, and the median peel strength obtained was used for evaluation.

[0093] Example 1 A carboxyl group-containing acrylic rubber composition was prepared by kneading 100 parts by weight of carboxyl group-containing acrylic rubber (Lacrestar CT, manufactured by Osaka Soda Co., Ltd.), 60 parts by weight of carbon black N550, 2 parts by weight of stearic acid, and 2 parts by weight of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (Nocrac CD, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) in a kneader at 120°C. Furthermore, 1 part by weight of tetramethylthiuram disulfide (Noccela TT, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 2 parts by weight of a mixture of 1,8-diazabicyclo(5.4.0)undecene-7 (DBU), a crosslinking retarder, and a binder resin (Rhenogran XLA-60, DBU content: 60% by weight, manufactured by Rhein Chemie) and 0.6 parts by weight of hexamethylenediamine carbamate (Sunfel 6-MC, manufactured by Sanshin Chemical Industry Co., Ltd.) in an open roll at room temperature.

[0094] The obtained carboxyl group-containing acrylic rubber composition was tested and evaluated for its normal physical properties (tensile strength, elongation, hardness), heat resistance, oil resistance, and peel strength by the above-mentioned methods. The results are shown in Table 1.

[0095] Examples 2 to 4 and Comparative Example 1 A carboxyl group-containing acrylic rubber composition was prepared in the same manner as in Example 1, except that the formulation was changed as shown in Table 1, and the same tests and evaluations were carried out as in Example 1. The results are shown in Table 1.

[0096] Examples 5 to 7 and Comparative Example 2 A carboxyl group-containing acrylic rubber composition was prepared in the same manner as in Example 1, except that the formulation was changed as shown in Table 2, and the same tests and evaluations were carried out as in Example 1. The results are shown in Table 2.

[0097] Example 8 100 parts by mass of Lacrestar CT, 60 parts by mass of Carbon Black N550, 2 parts by mass of stearic acid, 2 parts by mass of Nocrac CD, and 1.2 parts by mass of 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP, manufactured by Wakayama Seika Kogyo Co., Ltd.) were kneaded using a kneader at 120°C. Furthermore, 1 part by mass of Noccela TT and 2 parts by mass of Rhenogran XLA-60 were kneaded using an open roll at room temperature to prepare a carboxyl group-containing acrylic rubber composition.

[0098] The obtained carboxyl group-containing acrylic rubber composition was tested and evaluated for its normal physical properties (tensile strength, elongation, hardness), heat resistance, oil resistance, and peel strength by the above-mentioned methods. The results are shown in Table 3.

[0099] Comparative Example 3 A carboxyl group-containing acrylic rubber composition was prepared in the same manner as in Example 8, except that the formulation was changed as shown in Table 3, and the same tests and evaluations as in Example 8 were carried out. The results are shown in Table 3.

[0100] Example 9 100 parts by mass of Lacrestar CT, 60 parts by mass of Carbon Black N550, 2 parts by mass of stearic acid, and 2 parts by mass of Nocrac CD were kneaded using a kneader at 120°C. Furthermore, 0.5 parts by mass of Noccela TRA, 2 parts by mass of Rhenogran XLA-60, and 0.6 parts by mass of Sanfel 6-MC were kneaded using an open roll at room temperature to prepare a carboxyl group-containing acrylic rubber composition.

[0101] Using the obtained carboxyl group-containing acrylic rubber composition, normal physical properties (tensile strength, elongation, hardness), oil resistance (ΔV and ΔW only), and peel strength were tested and evaluated using the methods described above. Because the blending amount of component (B), which acts as an adhesive for the fluororubber composition, differs between Example 9 and Example 3, peel strength was primarily evaluated, and normal physical properties (tensile strength, elongation, hardness) and oil resistance (ΔV and ΔW only) were also evaluated. On the other hand, because Example 9 used the same blending system as Example 3, heat resistance and oil resistance (other than ΔV and ΔW) were not evaluated. The results are shown in Table 4.

[0102] Examples 10-11 A carboxyl group-containing acrylic rubber composition was prepared in the same manner as in Example 9, except that the formulation was changed as shown in Table 4, and the same tests and evaluations as in Example 9 were carried out. The results are shown in Table 4.

[0103] [Table 1]

[0104] [Table 2]

[0105] [Table 3]

[0106] [Table 4]

[0107] *1: Carboxyl group-containing acrylic rubber (Osaka Soda Co., Ltd., glass transition temperature: -26°C, Mooney viscosity (ML1+4, 100°C): 39) *2: 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (Ouchi Shinko Chemical Industry Co., Ltd.) *3: Tetramethylthiuram disulfide (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) *4: Tetraethylthiuram disulfide (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) *5: Dipentamethylenethiuram tetrasulfide (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) *6: 4,4'-Dithiodimorpholine (Ouchi Shinko Chemical Industry Co., Ltd.) *7: DBU (content: 60% by mass), a mixture of crosslinking retarder and binder resin (manufactured by Rhein Chemie) *8:DBU (Osaka Soda Co., Ltd.) *9: DBU naphthoate (Osaka Soda Co., Ltd.) *10: 1,3-di-o-tolylguanidine (Ouchi Shinko Chemical Industry Co., Ltd.) *11: 1,4-diazabicyclo[2.2.2]octane (Tokyo Chemical Industry Co., Ltd.) *12: Hexamethylenediamine carbamate (manufactured by Sanshin Chemical Industry Co., Ltd.) *13: 2,2-bis[4-(4-aminophenoxy)phenyl]propane (manufactured by Wakayama Seika Kogyo Co., Ltd.) Carbon black N550: Nitrogen adsorption specific surface area (N2SA): 41m 2 / g, average particle size: 43 nm (manufactured by Tokai Carbon Co., Ltd., product name: Seest SO) Carbon black N330: Nitrogen adsorption specific surface area (N2SA): 79m 2 / g, average particle size: 28 nm (manufactured by Tokai Carbon Co., Ltd., product name: Seast 3) Carbon Black N774: Nitrogen adsorption specific surface area (N2SA): 27m 2 / g, average particle size: 66 nm (manufactured by Tokai Carbon Co., Ltd., product name: Seast S)

[0108] As shown in Examples 1 to 8 in Tables 1 to 3, the normal state physical properties, heat resistance test and oil resistance test results of the carboxyl group-containing acrylic rubber cross-linked product of the present invention maintained physical properties comparable to those of Comparative Examples 1 to 3, and strong adhesion was confirmed with respect to the peel strength with peroxide-cross-linkable fluororubber.

[0109] Comparisons of Examples 1-4 with Comparative Example 1, and Examples 1, 5-7 with Comparative Example 2, confirmed that by satisfying the configuration of the present invention, adhesive strength with a fluororubber composition was improved without the need to incorporate an adhesion improver such as magnesium oxide into the fluororubber composition. Furthermore, comparisons of Example 1 with Example 8 confirmed that adhesive strength with peroxide-crosslinkable fluororubber did not change even when the crosslinking agent was changed. However, Comparative Example 3, which simulated Patent Publication 1 (Example 13), did not achieve adhesion with peroxide-crosslinkable fluororubber because the scorch time t5 was too long, at over 65 minutes. This suggests that strong adhesion with peroxide-crosslinkable fluororubber can be achieved by using a carboxyl group-containing acrylic rubber composition with a scorch time t5 of 60 minutes or less. [Industrial Applicability]

[0110] The carboxyl group-containing acrylic rubber composition of the present invention has excellent heat resistance and oil resistance, and further, the laminate of the present invention, in which a cross-linked product of the carboxyl group-containing acrylic rubber composition of the present invention and a cross-linked product of the fluororubber composition are laminated, has excellent peel strength and is industrially useful. The laminate of the present invention is suitably used as a hose or tube for fuel piping or air piping, taking advantage of the above properties.

Claims

1. (B) 0.1 to 10 parts by mass of a thiuram compound and / or a compound having an N—S bond, (C) 0.1 to 10 parts by mass of a tertiary amine and / or a guanidine compound, and (D) 0.1 to 6 parts by mass of an aliphatic diamine compound and / or an aromatic diamine compound, relative to 100 parts by mass of (A) a carboxyl group-containing acrylic rubber, A carboxyl group-containing acrylic rubber composition having a scorch time t5 at 125°C of 60 minutes or less.

2. 2. The carboxyl group-containing acrylic rubber composition according to claim 1, wherein the compound (B) having an N—S bond is 4,4′-dithiodimorpholine.

3. 3. The carboxyl group-containing acrylic rubber composition according to claim 1 or 2, wherein the tertiary amine and / or guanidine compound (C) is at least one selected from the group consisting of 1,8-diazabicyclo(5.4.0)undecene-7 and salts thereof, and 1,3-di-o-tolylguanidine.

4. The carboxyl group-containing acrylic rubber composition according to any one of claims 1 to 3, wherein the aliphatic diamine compound and / or aromatic diamine compound (D) is hexamethylenediamine carbamate and / or 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

5. A laminate obtained by laminating a cross-linked product of the carboxyl group-containing acrylic rubber composition according to any one of claims 1 to 4 and a cross-linked product of a fluororubber composition.

6. A tube or hose made of the laminate according to claim 5.

7. A fuel piping or air piping product comprising the tube or hose according to claim 6.

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