JP2007269008A - Heat-resistant air hose - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-resistant air hose in which interlayer adhesion is high and durability is excellent, and which is excellent in acid resistance, addition agent resistance or the like. <P>SOLUTION: The heat-resistant air hose comprises a tubular inner layer 1 and an outer layer 2 prepared in contact with the periphery surface, wherein the inner layer 1 is formed by using a rubber composition which comprises following (A)-(D) as essential components, and wherein component (C) and component (D) are blended at a proportion of (C)/(D)≤1/3 by weight ratio. (A) is an iodine containing fluororubber having 64-69 mass% of a fluorine content. (B) is an organic peroxide cross-linking agent. (C) is a triallyl isocyanurate, and (D) is ethylen glycol dimethacrylate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat-resistant air hose, and more particularly to a heat-resistant air hose useful as an automotive air hose (turbo air hose, blow-by gas hose, emission control hose, etc.).

  In recent years, exhaust gas regulations for diesel vehicles have been tightened, and the introduction of a new engine system (common rail fuel injection system) corresponding to that has been in full swing. In the above system, the engine is operated by injecting fuel at a high temperature and a high pressure so as to increase the combustion efficiency for the purpose of low exhaust gas. Similarly, turbochargers (superchargers) installed in most diesel vehicles also have a high supercharging pressure for the same purpose.

  The air hose (turbo air hose) attached to the turbocharger has a role of supplying high-pressure air from the turbocharger to the engine, as well as a mist of fuel vapor / engine oil once discharged from the engine. It is also responsible for re-supplying the engine with a mixture of air and re-burning it. For this reason, the turbo air hose is required to have high heat resistance and pressure resistance.

Conventionally, acrylic rubber has been used as a material for forming heat-resistant air hoses of this type of automobiles, but in recent years, the demand for heat resistance has become stricter. Excellent silicone rubber is used. However, since the silicone rubber is inferior in oil permeation resistance, during use, mist-like oil mixed in the air circulating in the air hose soaks into the rubber from the inner surface of the hose and reaches the outer surface of the hose. There is a problem that oil oozes out. Therefore, an inner tube rubber made of fluororubber (FKM) having excellent barrier properties or a blend rubber of fluororubber and acrylic rubber or fluorosilicone rubber is provided on the inner circumference of a silicone rubber layer formed using silicone rubber as a base material. In addition to forming a layer, a reinforcing yarn layer is formed on the silicone rubber layer, and an upper rubber layer made of silicone rubber or acrylic rubber is further formed on the reinforcing yarn layer to suppress oil seepage phenomenon. An air hose has been proposed (see, for example, Patent Document 1).
JP 2000-193152 A

  However, the heat-resistant air hose disclosed in Patent Document 1 has a problem in adhesion between the fluorine-based rubber layer (inner tube rubber layer) and the silicone rubber layer. For example, the heat resistance and pressure resistance described above. When used in turbo air hose applications that require high performance, delamination is likely to occur, which may cause various problems. The fluoro rubber used for the inner tube rubber layer is usually a polyol vulcanized fluoro rubber having excellent heat resistance. In this type of polyol vulcanized system, the viscosity added to the engine oil is high. It is inferior in resistance (additive resistance) to regulators and the like, and resistance to sour fuel (acid resistance) generated with increasing fuel temperature.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a heat-resistant air hose having high interlayer adhesion and excellent durability, and excellent acid resistance and additive resistance.

In order to achieve the above object, the heat-resistant air hose of the present invention is a heat-resistant air hose comprising a tubular inner layer and an outer layer provided in contact with the outer peripheral surface, and the inner layer is the following (A) Formed by using a rubber composition in which (D) is an essential component and the (C) component and (D) component are blended in a weight ratio of (C) / (D) ≦ 1/3 It is configured to be.
(A) An iodine-containing fluororubber having a fluorine content of 64-69% by mass.
(B) Organic peroxide crosslinking agent.
(C) Triallyl isocyanurate.
(D) Ethylene glycol dimethacrylate.

  That is, the present inventors have intensively studied to solve the above problems. In the course of the research, it was confirmed that it is advantageous to make the inner layer of the hose into a fluorine rubber (FKM) layer having excellent barrier properties. In addition, at present, only the use of polyol vulcanized FKM has been established, but as mentioned above, it was also confirmed that it is difficult to adopt polyol vulcanized from the viewpoint of acid resistance and additive resistance. . Therefore, the present inventors have recalled that organic peroxide vulcanization (peroxide crosslinking) FKM is used as the inner layer material, thereby solving the problems of acid resistance and additive resistance. However, the organic peroxide vulcanization system FKM is liable to cause a solvent crack due to adhering engine oil or the like, and is inferior in adhesion to the outer rubber (outer layer). Therefore, the present inventors have further studied for improving crack propagation (solvent cracking) and interlayer adhesion, and as a result, as a material for forming the inner layer, iodine containing 64 to 69% by mass of fluorine is contained. When fluorine rubber is used and triallyl isocyanurate and ethylene glycol dimethacrylate are contained in a specific ratio and vulcanized with an organic peroxide, excellent interlayer adhesion is obtained and the above-mentioned crack propagation property is obtained. It has been found that the problem of (solvent cracking) can be solved, and the present invention has been achieved.

  As described above, the heat-resistant air hose of the present invention includes a tubular inner layer (fluororubber layer) and an outer layer provided in contact with the outer peripheral surface, and the inner layer has a fluorine content of 64 to 69 mass. % Iodine-containing fluororubber, an organic peroxide crosslinking agent, triallyl isocyanurate, and ethylene glycol dimethacrylate as essential components, and the triallyl isocyanurate and ethylene glycol dimethacrylate in a specific ratio It is formed using a blended rubber composition. Therefore, the heat-resistant air hose of the present invention has excellent heat resistance and oil oozing resistance, and has high interlaminar adhesion, so it is extremely excellent in quality reliability. Furthermore, it is excellent in acid resistance and additive resistance. This makes it possible to exhibit excellent performance as a heat-resistant air hose such as a turbo air hose that requires high temperature and high pressure resistance.

  In particular, when the inner layer is formed using a rubber composition containing magnesium oxide (MgO) as an acid acceptor together with the essential components, the magnesium oxide functions as a propellant for deHF (hydrofluoric acid). , Interlayer adhesion becomes higher.

  Further, when the inner layer is formed using a rubber composition containing dipentamethylene thiuram tetrasulfide as a scorch inhibitor together with the essential components, the scorch property of the inner layer is improved, and extrusion processability and interlayer adhesion are improved. It becomes more excellent in sex.

  Further, the outer layer is made of acrylic rubber (ACM), ethylene-acrylic rubber (AEM), silicone rubber (VMQ), ethylene-propylene-diene terpolymer rubber (EPDM), ethylene-propylene rubber (EPM), etc. When used, it can exhibit excellent performance especially as a heat-resistant air hose for automobiles, and more excellent in interlayer adhesion with the inner layer formed by organic peroxide vulcanization. become.

  Next, embodiments of the present invention will be described in detail.

  The heat-resistant air hose of the present invention is characterized in that the inner layer is formed using a fluororubber containing a specific component. For example, as shown in FIG. 1, the layer structure includes a two-layer structure including the inner layer (fluororubber layer) 1 and an outer layer 2 provided in contact with the outer peripheral surface thereof. Further, as shown in FIG. 2, a reinforcing yarn layer 3 is formed on the outer peripheral surface of the outer layer 2, and a rubber outermost layer 4 is formed on the outer peripheral surface of the reinforcing yarn layer 3 to constitute a heat-resistant air hose. May be. In addition, as shown in FIG. 3, a reinforcing yarn layer 3 is provided between the inner layer 1 and the outer layer 2, and the adhesiveness (interlayer) between the inner layer 1 and the outer layer 2 through the weave of the reinforcing yarn layer 3. It is good also as a structure which can obtain adhesiveness.

  In the present invention, as described above, the inner layer 1 includes an iodine-containing fluororubber having a fluorine content of 64 to 69% by mass (component (A)) and an organic peroxide crosslinking agent [component (B). ], Triallyl isocyanurate [component (C)] and ethylene glycol dimethacrylate [component (D)], and the component (C) and component (D) are blended at a specific ratio. It is formed using a rubber composition.

  As the iodine-containing fluororubber as the component (A), those having a fluorine content of 64 to 69% by mass are used. The fluorine content is preferably in the range of 66 to 69% by mass. That is, if the fluorine content is less than 64% by mass, it is inferior in compression set (sealability), and conversely, if it exceeds 69% by mass, it is inferior in extrudability and low temperature. .

  Here, the iodine-containing fluororubber as the component (A) refers to a fluorinated polymer that has rubber elasticity at room temperature when vulcanized. Conventionally known fluororubbers are included, and typical fluororubbers include vinylidene fluoride / hexafluoropropylene, vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene, and vinylidene fluoride / chlorotrifluoroethylene. Fluoro rubbers such as tetrafluoroethylene / propylene, hexafluoropropylene / ethylene, perfluoroalkyl vinyl ether / olefin (tetrafluoroethylene, ethylene, etc.), fluorosilicone, fluorophosphazene, and the like. Examples of iodine-containing fluororubber are described in, for example, Japanese Patent Publication No. 5-63482 and Japanese Patent Laid-Open No. 7-315234. That is, the iodine-containing fluororubber contains an iodine-containing compound [for example, perfluoro (6,6-dihydro-6-iodo-3-oxa-) in addition to the above-mentioned fluororubber monomer (for example, vinylidene fluoride). 1-hexene), perfluoro (5-iodo-3-oxa-1-pentene, etc.)] and the like. The iodine-containing fluororubber may be used alone or in combination of two or more. Among these, from the viewpoint of interlayer adhesion by organic peroxide crosslinking and solvent cracking properties, the above-mentioned fluororubber monomers are vinylidene fluoride / hexafluoropropylene, vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene. Are preferred.

  In addition, as a commercial item of the iodine containing fluororubber of the said (A) component, Daiel G801 etc. by Daikin Industries, Ltd. can be used as a suitable thing, for example.

  Examples of the organic peroxide crosslinking agent [component (B)] used together with the component (A) include 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1. -Bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) cyclododecane, 1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,4-bis (t-butylperoxy) butane, n-butyl-4, Peroxyketals such as 4-bis (t-butylperoxy) valerate, di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide α, α′-bis (t-butylperoxy-m-isopropyl) benzene, α, α′-bis (t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5-di (t-butyl) Peroxy) hexane, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3, dialkyl peroxides, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl Diacyl peroxides such as peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, m-trioyl peroxide, and t-butyl peroxide Oxyacetate, t-butyl peroxyisobutyrate, t-butylperoxy-2-ethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate, di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di ( Benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, peroxyesters such as cumylperoxyoctate, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydro And hydroperoxides such as peroxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3, -tetramethylbutyl peroxide, and the like. These may be used alone or in combination of two or more.

  The blending ratio of the component (B) is set in the range of 0.1 to 5 parts with respect to 100 parts by weight (hereinafter abbreviated as “part”) of the iodine-containing fluororubber of the component (A). Preferably, it is in the range of 0.2 to 4 parts. That is, if the organic peroxide cross-linking agent [component (B)] is less than 0.1 part, the cross-linking is insufficient and the hose strength and sealability are deteriorated. This is because if it exceeds 5 parts, it becomes too hard and the flexibility of the hose tends to be impaired.

  In the present invention, together with the components (A) and (B), a polyfunctional monomer (co-crosslinking agent) such as triallyl isocyanurate [(C) component] and ethylene glycol dimethacrylate [(D) component] And used as an essential component of the rubber composition for forming the inner layer 1. Further, the component (C) and the component (D) must be blended at a weight ratio of (C) / (D) ≦ 1/3. In other words, the stress at the time of stretching can be relieved by setting such a ratio and forming a gentle cross-linking structure with the component (D), and the physical properties at the normal state can be improved by adding a small amount of the component (C). These have led to improvements in crack propagation (solvent cracking). Therefore, when the ratio of the component (C) to the component (D) is (C) / (D)> 1/3 by weight, the crack propagation property (solvent crack property) of the inner layer 1 is solved. Can not do it.

  Further, the blending ratio of the component (C) and the component (D) to the component (A) (iodine-containing fluororubber) is not particularly limited as long as the blend ratio is satisfied. From the viewpoint of strength and sealing properties, the component (C) is preferably set in a range of 0.1 to 2 parts, more preferably 0.2 to 1 with respect to 100 parts of the component (A). .5 parts range. From the same viewpoint, the component (D) is preferably set in the range of 1 to 10 parts, more preferably in the range of 2 to 8 parts, relative to 100 parts of the component (A).

  By the way, in the rubber composition for forming the inner layer 1 in the heat-resistant air hose of the present invention, in addition to the components (A) to (D) as essential components, magnesium oxide [( E) component] is preferable because this magnesium oxide functions as a propellant for deHF (hydrofluoric acid) and the interlaminar adhesion becomes higher.

  The blending ratio of the component (E) is preferably set in the range of 0.1 to 20 parts, more preferably 1 to 10 parts with respect to 100 parts of the iodine-containing fluororubber of the component (A). It is a range. That is, by including magnesium oxide [(E) component] within this range, an improvement effect such as interlayer adhesion can be obtained.

  In addition to the above components (A) to (D), if necessary, dipentamethylene thiuram tetrasulfide [component (F)] is added as a scorch inhibitor, so that the scorch property of the inner layer is improved. It is preferable because the processability and interlayer adhesion become more excellent.

  The blending ratio of the component (F) is preferably set in the range of 0.05 to 2 parts, more preferably 0.1 to 1 with respect to 100 parts of the iodine-containing fluororubber of the component (A). Part range. That is, by including dipentamethylene thiuram tetrasulfide [component (F)] within this range, an effect of improving the scorch property can be obtained.

  The material for the inner layer 1 may contain carbon black, processing aids, coloring agents, and the like as necessary together with the above components.

  Although the outer layer 2 formed on the outer peripheral surface of the inner layer 1 is not particularly limited as a forming material, the outer layer 2 is made of acrylic rubber (ACM), ethylene-acrylic rubber (AEM), silicone rubber (VMQ), ethylene. -When formed using propylene-diene terpolymer rubber (EPDM), ethylene-propylene rubber (EPM), etc., it can exhibit particularly excellent performance as a heat-resistant air hose for automobiles, Since the material can be organic peroxide-crosslinked, the interlayer adhesion with the inner layer 1 formed by organic peroxide crosslinking is further improved. And these materials are used individually or in combination of 2 or more types. In addition, in the forming material of the outer layer 2, carbon black, an antioxidant, a vulcanizing agent, a vulcanization accelerator, a processing aid, a white filler, a plasticizer, a softening agent, and an acid acceptor are included as necessary. Further, a coloring agent, a scorch prevention agent and the like may be added as appropriate.

  2 and 3, examples of the reinforcing yarn forming the reinforcing yarn layer 3 provided between the layers include vinylon (polyvinyl alcohol) yarn, polyamide (nylon) yarn, aramid yarn, polyethylene terephthalate (PET) yarn. Etc.

  The method for braiding the reinforcing yarn is not particularly limited, and examples thereof include spiral knitting, knitting knitting, and blade knitting.

  In addition, in FIG. 2, the material for forming the outermost layer 4 provided on the outer periphery of the reinforcing yarn layer 3 is not particularly limited, but usually the same rubber composition as that of the outer layer 2 is used.

  Here, the heat-resistant air hose shown in FIG. 1 can be manufactured as follows, for example. That is, first, the component materials (A) to (D) are prepared, and other component materials ((E), (F) component materials, etc.) are also prepared as necessary, and these are opened rolls or kneaders. A material composition for the inner layer 1 is prepared by kneading using a closed mixer such as the above. Further, a material composition for the outer layer 2 is also prepared by using the appropriate material and the same method. Next, after extruding the material composition for the inner layer 1 into a cylindrical shape, the material composition for the outer layer 2 is directly applied to the inner layer 1 without applying an adhesive to the surface (without an adhesive). A heat-resistant air hose in which the outer layer 2 is formed on the outer peripheral surface of the inner layer 1 can be obtained by extrusion molding on the material composition and vulcanizing these layers. The above layers may be formed by coextrusion molding.

  Moreover, the heat-resistant air hose of the present invention shown in FIG. 3 can be manufactured as follows, for example. That is, a composition for each layer is prepared by the same method as described above, and the material composition for the inner layer 1 is extruded into a cylindrical shape, and then a reinforcing thread is braided into a blade shape on the surface. Subsequently, the outer layer 2 material composition is extruded on the outer peripheral surface of the reinforcing yarn, and these layers are vulcanized to form the reinforcing yarn layer 3 on the outer peripheral surface of the inner layer 1. A heat-resistant air hose in which the outer layer 2 is formed on the outer peripheral surface of 3 can be obtained. The hose shown in FIG. 2 has a reinforcing yarn layer 3 formed on the outer periphery of the hose shown in FIG. 1 in the same manner as described above, and a rubber composition for forming the outermost layer 4 on the outer peripheral surface of the reinforcing yarn layer 3. It can be manufactured by extruding the product.

  In the heat-resistant air hose of the present invention thus obtained, the inner diameter of the hose is preferably in the range of 30 to 100 mm, particularly preferably in the range of 30 to 70 mm. The thickness of the inner layer 1 is preferably in the range of 0.05 to 20 mm, particularly preferably in the range of 0.1 to 10 mm, and the thickness of the outer layer 2 is preferably in the range of 0.05 to 20 mm, particularly preferably. Is in the range of 0.1 to 10 mm.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to these examples.

  First, prior to the examples and comparative examples, the following materials were prepared.

[FKM polymer (component A)]
Daiel G801 (Iodine-containing fluororubber with a fluorine content of 66% by mass), manufactured by Daikin Industries, Ltd.

〔Carbon black〕
Seast S, manufactured by Tokai Carbon

[MgO (E component)]
Kyowa Mug # 150, manufactured by Kyowa Chemical Industry Co., Ltd.

[Organic peroxide cross-linking agent (component B)]
Perhexa 25B-40 [2,5-dimethyl-2,5-di (t-butylperoxy) hexane], manufactured by NOF Corporation

[Co-crosslinking agent (i) (C component)]
Thaik (triallyl isocyanurate), manufactured by Nippon Kasei Co., Ltd.

[Co-crosslinking agent (ii) (component D)]
High Cloth ED (ethylene glycol dimethacrylate), manufactured by Seiko Chemical Co., Ltd.

[Scorch inhibitor (F component)]
Noxeller TRA (dipentamethylene thiuram tetrasulfide), manufactured by Ouchi Shinsei Chemical Co., Ltd.

[Examples 1-20, Comparative Examples 1-15]
First, the above-prepared component materials are blended in the proportions shown in Table 1 below, and are kneaded using a closed mixer such as an open roll or a kneader to produce an inner layer material (a material composition for a fluororubber layer). A) to g were prepared.

  Further, as shown below, outer layer materials (ACM layer material composition, AEM layer material composition, VMQ layer material composition, EPDM layer material composition, and EPM layer material composition) were prepared.

[Preparation of ACM layer material composition]
100 parts of ACM polymer (Nipol AR31, manufactured by Nippon Zeon Co., Ltd.), 1 part of processing aid (Lunac S30, manufactured by Kao Corporation), 65 parts of carbon black (Seast SO, manufactured by Tokai Carbon Co., Ltd.), plasticizer (Adekasizer) RS735, manufactured by Asahi Denka Kogyo Co., Ltd.), anti-aging agent (Nauguard 445, manufactured by Crompton Co., Ltd.) 2 parts, and vulcanizing agent (Barnock AB, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1.5 parts, open roll Alternatively, an outer layer material (ACM layer material composition) was prepared by kneading using a closed mixer such as a kneader.

[Preparation of AEM layer material composition]
100 parts of AEM polymer (VAMAC GLS, manufactured by DuPont), 2 parts of processing aid (Lunac S30, manufactured by Kao Corporation), 60 parts of carbon black (Seast SO, manufactured by Tokai Carbon Co., Ltd.), and anti-aging agent (Naugard 445) 2 parts of Crompton), 0.5 parts of processing aid (Armin 18D, Lion Akzo), 4 parts of processing aid (Phosphanol RL210, Toho Chemical Industries), and vulcanizing agent Kneading 1.5 parts (Diac # 1, DuPont) and 4 parts vulcanization aid (Noxeller DT, Ouchi Shinsei Chemical) using a closed mixer such as an open roll or a kneader. Thus, an outer layer material (AEM layer material composition) was prepared.

[Preparation of material composition for VMQ layer]
100 parts of VMQ polymer (ELASTOSIL R760 / 70 OH, manufactured by Asahi Kasei Wacker Silicone Co.) and 1.8 parts of vulcanizing agent (DS-3, manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) are used as a closed mixer such as an open roll or a kneader. The outer layer material (material composition for VMQ layer) was prepared by kneading using

[Preparation of EPDM layer material composition]
100 parts of EPDM polymer (Esprene 501A, manufactured by Sumitomo Chemical Co., Ltd.), 150 parts of carbon black (Seast SO, manufactured by Tokai Carbon Co., Ltd.), 50 parts of process oil (Diana Process PW380, manufactured by Idemitsu Kosan Co., Ltd.), and an antioxidant (Nonflex RD, manufactured by Seiko Chemical Co., Ltd.) Was kneaded using a closed mixer such as an open roll or a kneader to prepare an outer layer material (EPDM layer material composition).

[Preparation of EPM layer material composition]
100 parts of EPM polymer (Esplen 201, manufactured by Sumitomo Chemical Co., Ltd.), 150 parts of carbon black (Shiest SO, manufactured by Tokai Carbon Co., Ltd.), 50 parts of process oil (Diana Process PW380, manufactured by Idemitsu Kosan Co., Ltd.), and an antioxidant 1 part (Nonflex RD, manufactured by Seiko Chemical Co., Ltd.), 7 parts of peroxide cross-linking agent (Perhexa 25B-40, manufactured by Nippon Oil & Fats Co., Ltd.), 3 parts of cross-linking aid (Hicross ED, manufactured by Seiko Chemical Co., Ltd.) Was kneaded using a closed mixer such as an open roll or a kneader to prepare an outer layer material (EPM layer material composition).

[Production of hose]
Inner layer materials (fluorine rubber layer material composition) a to g and outer layer materials (ACM layer material composition, AEM layer material composition, VMQ layer material composition, EPDM layer material composition and EPM layer use) Material compositions) were used in combinations shown in Tables 2 to 6 below to produce heat resistant air hoses. That is, after the inner layer material is extruded into a cylindrical shape, the outer layer material is directly extruded without applying an adhesive to the surface (without an adhesive), and each of these layers is steam vulcanized (160 ° C. X45 minutes), a heat-resistant air hose having a two-layer structure in which the outer layer was formed on the outer peripheral surface of the inner layer was obtained (see FIG. 1). The heat-resistant air hose was prepared so that the inner layer had a thickness of 2.5 mm, the outer layer had a thickness of 2.5 mm, and the hose inner diameter was 40 mm.

  Using each heat resistant air hose thus obtained, various properties were measured and evaluated according to the following methods. These results are shown in Tables 2 to 6 below.

(Interlayer adhesion)
A test piece having a thickness of 3 mm (inner layer thickness of 1.5 mm, outer layer thickness of 1.5 mm) and width of 25.4 mm was cut out from each hose, and the inner layer (fluororubber layer) of the test piece was removed from a tensile tester (JIS B). 7721), and peeled off at a rate of 50 mm per minute, and the interlayer adhesion (N / mm) at that time was measured. The interlayer adhesion required for the present invention is 2.0 N / mm or more.

[Crack propagation (solvent cracking)]
A notch scratch is made in the center of a JIS No. 1 dumbbell cut out from the inner layer of each hose, and this dumbbell is stretched by 50% and then immersed in a diesel engine oil (10 W-30) at 150 ° C. for about 10 seconds. Subsequently, the sample was left in an atmosphere at 150 ° C., and the time (minutes) until cutting was measured to evaluate crack progress (solvent crack property).

  From the above results, the products of all the examples obtained excellent results in interlayer adhesion and crack propagation (solvent crack property).

  On the other hand, Comparative Examples 1, 4, 7, 10 and 13 did not use the co-crosslinking agent (ii) (ethylene glycol dimethacrylate) as the inner layer material and evaluated crack progressability (solvent crack property). It turns out that it is inferior to. It can be seen that Comparative Examples 3, 6, 9, 12, and 15 do not use the co-crosslinking agent (i) (triallyl isocyanurate) as the inner layer material, and are inferior in evaluation of interlayer adhesion. In Comparative Examples 2, 5, 8, 11 and 14, the co-crosslinking agents (i) and (ii) are used for the inner layer material, but the ratio does not satisfy the provisions of the present invention, and the crack progressability Even in the evaluation of (solvent crack property) and the like, it is understood that the standard required for the present invention is not satisfied.

  By the way, regarding all the examples, when the reinforcing yarn layer was interposed between the layers (see FIG. 3), various performances similar to the above-mentioned all examples were confirmed, and the durability of the hose was further enhanced. For example, it was recognized that it can exhibit excellent performance as a high-pressure hose application such as a turbo air hose.

  The heat-resistant air hose of the present invention can be used for all air hoses that require heat resistance. Among them, automobile air hoses, in particular, fuel vapor, engine oil mist, and air It is useful as an air hose for discharging the mixture from the engine and supplying it to the engine for recombustion, more specifically, a turbo air hose, a blow-by gas hose, an emission control hose, and the like.

It is a block diagram which shows an example of the heat-resistant air hose of this invention. It is a block diagram which shows the other example of the heat-resistant air hose of this invention. It is a block diagram which shows the other example of the heat-resistant air hose of this invention.

Explanation of symbols

1 Inner layer 2 Outer layer

Claims (4)

A heat-resistant air hose comprising a tubular inner layer and an outer layer provided in contact with the outer peripheral surface, wherein the inner layer comprises the following (A) to (D) as essential components, and the (C) component ( A heat-resistant air hose characterized by being formed using a rubber composition in which component D) is blended in a weight ratio of (C) / (D) ≦ 1/3.
(A) An iodine-containing fluororubber having a fluorine content of 64-69% by mass.
(B) Organic peroxide crosslinking agent.
(C) Triallyl isocyanurate.
(D) Ethylene glycol dimethacrylate. The heat resistant air hose according to claim 1, wherein the inner layer is formed using a rubber composition containing the following component (E) as an acid acceptor together with the essential components (A) to (D).
(E) Magnesium oxide. The heat-resistant air hose according to claim 1 or 2, wherein the inner layer is formed by using a rubber composition containing the following component (F) as a scorch inhibitor together with the essential components (A) to (D). .
(F) Dipentamethylene thiuram tetrasulfide.   The outer layer is made of a group consisting of acrylic rubber (ACM), ethylene-acrylic rubber (AEM), silicone rubber (VMQ), ethylene-propylene-diene terpolymer rubber (EPDM) and ethylene-propylene rubber (EPM). The heat-resistant air hose according to any one of claims 1 to 3, wherein the heat-resistant air hose is formed using at least one selected.

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