Automotive Fuel Hose-4 Mar 2004

8/6/2019 Automotive Fuel Hose-4 Mar 2004

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1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1us 20040040608Al(19) United States(12) Patent Application PublicationIto et ai. (10) Pub. No.: US 2004/0040608 Al(43) Pub. Date: Mar. 4, 2004

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(54) AUTOMOTIVE FUEL HOSE(75) Inventors: Hiroaki Ito, Kasugai-shi (lP);

Kazutaka Katayama, Kasugai-shi (lP);Junichiro Suzuki, Kasugai-shi (lP)

Correspondence Address:ARMSTRONG, KRATZ, QUINTOS, HANSON& BROOKS, LLP1725 K STREET, NWSUITE 1000WASHINGTON, DC 20006 (US)

(73) Assignee: TOKAI RUBBER INDUSTRIES,LTD., Komaki-shi (lP)

(21)(22)

Appl. No.: 10/648,473Filed: Aug. 27, 2003

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(30) Foreign Application Priority DataAug. 30, 2002 (lP) lP2002-254581

Publication Classification(51) Int. CI? F16L ll/OO(52) U.S. CI. 138/137; 138/141; 428/36.91(57) ABSTRACTAn automotive fuel hose of low fuel permeability, andexcellent in impact resistance, hydrolysis resistance, andinter-layer adhesion. The automotive fuel hose comprises: atubular inner layer (1) comprising a fluororesin having afunctional group; and a low fuel permeability layer (2)comprising a polyester resin having a naphthalene ring; theinner layer in which fuel is adapted to flow; the low fuelpermeability layer being laminated onto the inner layer suchthat respective mating interfaces contact each other.


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Patent Application Publication Mar. 4, 2004 US 2004/0040608Al

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AUTOMOTIVE FUEL HOSEBACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention[0002] The present invention relates to an automotive fuelhose for transportation of an automotive fuel, specifically toan automotive fuel hose for transportation of gasoline,alcohol-containing gasoline, diesel fuel or the like.[0003] 2. Description of the Art[0004] With growing worldwide awareness of environ-mental issues, the control of the amount of hydrocarbonvapor emission from an automotive fuel hose has beenenhanced. Particularly in the United States, stringent regu-lations against vapor emission have recently come intoeffect. To cope with the hydrocarbon vapor emission controlin this situation, multi-layer hoses have been proposedwhich include a layer having low fuel permeability such ascomposed of a fluororesin, a polyester resin or a polyp he-nylene sulfide (PPS) resin. A multi-layer hose including afluororesin layer has a relatively low permeability. To satisfya stricter low-permeability requirement, the thickness of thefluororesin layer should be increased, resulting in corre-spondingly higher costs. On the other hand, the polyesterresin and the PPS resin are higher in permeation resistancethan the fluororesin and, therefore, a layer composed of thepolyester resin or the PPS resin has a satisfactory permeationresistance even if it has a relatively small thickness. Thepolyester resin layer and the PPS resin layer are advanta-geous in terms of costs, but have difficulty in laminationbecause of their poorer adhesion.[0005] To solve the aforesaid drawback, the followinghoses (1) to (5) have been proposed.[0006] As proposed in Japanese Patent No. 3126275, ahose (1) has a five-layer structure consisting of a fluororesinlayer, a first adhesive resin layer, a polybutylene naphthalatelayer, a second adhesive resin layer and a thermoplastic resinlayer stacked in this order from the inner side thereof. Thefirst adhesive resin layer for bonding the fluororesin layerand the polybutylene naphthalate layer is formed by amixture of a fluorine-containing material and a crystallinepolyester or a polyester elastomer blended with a compati-bilizing agent.[0007] As proposed in Japanese Unexamined Patent Pub-lication No. 7-173446 (1995), a hose (2) comprises an innerlayer formed by a graft-modified ETFE (a copolymer ofethylene and tetrafluoroethylene) and an outer layer formedby a polybutylene terephthalate provided on an outer periph-eral surface of the inner layer.[0008] As proposed in International Publication No.W098/58973, a hose (3) has a laminated structure of a layercomprising tetrafluoroethylene copolymer wherein termi-nals are modified with polycarbonate and a layer comprisingat least one other polymer such as a polyamide resin, apolyolefin resin or epoxy resin.[0009] As proposed in International Publication No.W098/55557, a hose (4) has a laminated structure of a layerformed by a copolymer consisting of (a) a fluorine-contain-ing ethylene monomer having a carboxyl group or a car-boxylate and (b) a fluorine-containing ethylene monomercapable of copolymerization with the above-mentioned (a)

Mar. 4, 20041

and not containing any of the above-mentioned functionalgroups, and a layer comprising a thermoplastic resin.[0010] As proposed in International Publication No.W098/45044, a hose (5) has a laminated structure of a layercomprising a fluorine-containing ethylene polymer having acarbonate group or a carboxylic halide group and a layercomprising at least one other polymer such as a polyamideresin, a polyester resin or a polycarbonate resin.[0011] However, hose (1) is disadvantageous in that adhe-sion between the innermost fluororesin layer and the inter-mediate polybutylene naphthalate layer is very poor. If theadhesion between the inner layer and the intermediatepolybutylene naphthalate layer which serves to prevent thepermeation of a fuel is insufficient, the inner layer tends todelaminate, thereby reducing the inner space of the hose.This may result in clogging of the hose or reduction in theflow rate of the fuel through the hose. Since the first adhesiveresin layer for bonding the fluororesin layer and the poly-butylene naphthalate layer is formed by a mixture with afluorine-containing material, the resultant layer is disadvan-tageous in that impact resistance is poor and cost becomeshigh. Since the outer layer of the above hose (2) is formedby a polybutylene terephthalate, the resultant hose has highfuel permeability and poor hydrolytic resistance due tohydrolysis with alcohol or water contained in fuel. Theabove hoses (3) to (5) are insufficient in fuel permeability,impact resistance and inter-layer adhesion.[0012] In view of the foregoing, it is an object of thepresent invention to provide an automotive fuel hose excel-lent in low fuel permeability, impact resistance, hydrolysisresistance and inter-layer adhesion.

SUMMARY OF THE INVENTION[0013] In accordance with the present invention to achievethe aforesaid object, there is provided an automotive fuelhose, which comprises: a tubular inner layer comprising afluororesin having a functional group; and a low fuel per-meability layer comprising a polyester resin having a naph-thalene ring; the inner layer in which fuel is circulated; thelow fuel permeability layer being laminated onto the innerlayer such that respective mating interfaces contact eachother.[0014] The inventors of the present invention conductedintensive studies to provide an automotive fuel hose excel-lent in low fuel permeability, impact resistance, hydrolysisresistance and inter-layer adhesion. As a result, it was foundthat, where an inner layer is formed by a fluororesin havinga functional group and a low fuel permeability layer isformed by a polyester resin having a naphthalene ring on anouter peripheral surface of the inner layer, adhesion betweenthe inner layer and the low fuel permeability layer can beenhanced. This is because the functional groups of thefluororesin interact with terminal carboxyl groups or termi-nal hydroxyl groups of the polyester resin having the naph-thalene ring. At the first stage of the studies, the inventorsthought that the polyester resin having the naphthalene ring,such as a polybutylene naphthalate or a polyethylene naph-thalate, has poor reactivity with the fluororesin having thefunctional group, resulting in poor adhesion, because thenaphthalene ring causes steric hindrance. However, as aresult of further experiments, the inventors found that theadhesion with the fluororesin having the functional group is


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better in the case of using polyester resin having the naph-thalene ring, such as a polybutylene naphthalate or a poly-ethylene naphthalate, than in the case of using a polybuty-lene terephthalate which is thought to have less sterichindrance due to no naphthalene ring. Thus, the presentinvention has been attained.

BRIEF DESCRIPTION OF THE DRAWINGS[0015] The sole figure of the drawing is a diagram illus-trating the construction of an exemplary fuel hose accordingto the present invention.

DESCRIPTION OF THE PREFERREDEMBODIMENTS

[0016] Embodiments of the present invention will herein-after be described in detail.[0017] As shown in Figure, an automotive fuel hoseaccording to one embodiment of the present inventionincludes an inner layer 1 in which fuel is circulated and a lowfuel permeability layer 2 provided on an outer peripheralsurface of the inner layer 1. The inner layer 1 and the lowfuel permeability layer 2 are directly provided such thatrespective mating interfaces contact each other, no applica-tion of an adhesive or no plasma treatment is required on theinterfaces.[0018] The fluororesin having the functional group isemployed as a material for the inner layer 1.[0019] The fluororesin is not particularly limited, butexamples thereof include a copolymer of ethylene andtetrafluoroethylene (ETFE); a copolymer of tetrafluoroeth-ylene and hexafluoropropylene (FEP); a copolymer of eth-ylene and chlorotrifluoroethylene (ECTFE); a copolymer ofvinylidene fluoride and hexafluoropropylene; a copolymerof vinylidene fluoride and chlorotrifluoroethylene; a copoly-mer of vinylidene fluoride and tetrafluoroethylene; a copoly-mer ofvinylidene fluoride, tetrafluoroethylene and hexafluo-ropropylene (THV); a copolymer of vinylidene fluoride,tetrafluoroethylene, hexafluoropropylene and perfluoro-alkoxyvinyl ether; and a copolymer of tetrafluoroethylene,vinylidene fluoride, hexafluoropropylene, and perfluoro-alkoxyvinyl ether. These fluororesins may be used eitheralone or in combination. Among these fluororesins, ETFEand THV are particularly preferred because of their excellentworkability.[0020] The functional group for the fluororesin is notparticularly limited, but examples thereof include an epoxygroup, a hydroxyl group, a carboxylic anhydride residualgroup, an acrylate group and an amino group.[0021] The fluororesin having the functional group may beobtained by grafting a grafted compound having a functionalgroup in the fluororesin or copolymerizing a compoundhaving a functional group in its main chain or at a terminalof the fluororesin.[0022] The impact strength of the fluororesin having thefunctional group preferably is not less than 30 Jim at _40c., more preferably not less than 45 Jim. The impact strengthmay be measured in accordance with ASTM D256 (notchedizod).[0023] The inner layer 1 may be electrically conductive soas not to charge fuel with static electricity mainly generated

Mar. 4, 20042

by a fuel pump. Thus, an accident such as ignition of the fuelcaused by a spark can effectively be prevented. In this case,an electrically conductive material such as carbon black,carbon-nano tubes, metal powder or metal oxide powderpreferably is blended in the aforesaid inner layer material.Where the inner layer is thus imparted with electricalconductivity, the inner layer (electrically conductive layer)preferably has a surface electric resistance of not higher than106 Q, particularly preferably not higher than 105 Q. Theproportion of the electrically conductive material is prefer-ably determined so that the surface electrical resistance fallswithin the aforesaid range.[0024] The low fuel permeability layer 2 provided on theinner layer 1 is composed of a polyester resin having anaphthalene ring. Such a polyester resin is not particularlylimited, but examples thereof include a polybutylene naph-thalate (PBN) and a polyethylene naphthalate (PEN).[0025] Polybutylene naphthalate (PBN) is a resin obtainedby condensation between tetramethylene glycol and 2,6-naphthalenedicarboxylic acid or its ester compound. Poly-ethylene naphthalate (PEN) is a resin obtained by conden-sation between ethylene glycol and 2,6-naphthalenedicarboxylic acid or its ester compound.[0026] The PBN or the PEN may be copolymerized withan ether segment or an ester segment so as to be used as athermoplastic elastomer having flexibility within a range insuch a manner to satisfy the low permeability. Further, thePBN or the PEN may be reacted with a dicarboxylic acid ofa fatty acid in addition to naphthalene dicarboxylic acid insuch a manner to satisfy the low permeability. Alternatively,the PBN or the PEN may be mixed with an elastomer suchas an olefin elastomer or a fine-particle crosslinked elas-tomer in such a manner to satisfy the low permeability.[0027] The PBN or the PEN preferably may have apermeability coefficient of not higher than 0.08. The per-meability coefficient indicates a permeability coefficient(mg/mm/cm2/day/atm) of fuel composed of 90 volume %Fuel C (50% by volume of toluene+50% by volume ofisooctane) and 10 volume % ethanol at 40 C. The perme-ability coefficient is measured in conformity with "MethodA" of Japanese Industrial Standard (JIS) K7126.[0028] The PBN or the PEN preferably has a viscosity of90 to 260 cm3/g in consideration of a balance betweenextrudability and resistances to shock, heat and hydrolysis.The viscosity is determined at 35 C. in conformity withASTM D 2857 by employing a solution obtained by dis-solving the PBN or the PEN in a concentration of 0.005g/cm" in a solvent mixture of phenol and tetrachloroethane.[0029] The structure of the inventive automotive fuel hoseis not limited to that shown in Figure, but an outer layer (notshown) may be provided on an outer peripheral surface ofthe low fuel permeability layer 2 in consideration of pro-viding flexibility suitable for hoses as well as chippingresistance.[0030] The material for the outer layer is not particularlylimited, but examples thereof include polyamide resins suchas polyamide 6 (PA6), polyamide 66 (PA66), polyamide 612(PA612), polyamide 11 (PAll), polyamide 912 (PA912) andpolyamide 12 (PA12), a thermoplastic ester elastomer(TPEE), a thermoplastic polyolefin elastomer (TPO), a ther-moplastic polyamide elastomer (TPAE) and a thermoplastic


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polystyrene elastomer (TPS), which may be used eitheralone or in combination. The outer layer is not limited to asingle-layer structure and may have a multi-layer structureof two or more layers.[0031] The low fuel permeability layer 2 and the outerlayer may be bonded by means of an adhesive resin, asrequired. The specific adhesive resin is not particularlylimited, but examples of the adhesive resin include epoxyresins, polyamide resins (PA), and thermoplastic styreneelastomers. These adhesive resins may be used either aloneor in combination. A blend of a PEN, a polybutyleneterephthalate (PET), a thermoplastic PEN elastomer and/ora thermoplastic PET elastomer may be employed as theadhesive resin.[0032] In the present invention, the structure of the innerlayer 1is not limited to a single-layer structure as shown inFigure, but may be a multi-layer structure consisting of twoor more sublayers. For example, the inner layer 1may havea double-layer structure consisting of an electrically con-ductive inner sublayer and an electrically non-conductiveouter sublayer. Likewise, the outer layer may have a multi-layer structure consisting of two or more sublayers.[0033] The inventive automotive fuel hose shown in Fig-ure is produced, for example, by the following process. First,each material of the aforesaid fiuororesin having the func-tional group and of the aforesaid polyester resin having thenaphthalene ring are prepared for an inner layer 1and a lowfuel permeability layer 2, respectively. Each material isextruded by means of an inner-layer material extruder and alow fuel permeability material extruder, respectively, and iscombined in a die. The thus molten material is co-extrudedinto a tubular shape, which is passed through a sizing die, sothat the intended fuel hose wherein the low fuel permeabilitylayer is directly laminated onto an outer peripheral surfaceof the inner layer is produced. The formation of the innerlayer 1 having a double-layer structure is achieved bysimultaneously extruding each material from separateextruders and combining the resulting sublayers in a die. Forformation of the outer layer having a double-layer structure,the outer layer may be formed likewise in the aforesaidmanner. Further, when a hose is formed into a corrugatedhose, the aforesaid molten material co-extruded into a tubu-lar shape is passed through a corrugation forming machineso that a corrugated hose of specified dimensions may beformed.[0034] The inventive automotive fuel hose thus producedpreferably has an inner diameter of 4 to 40 mm, particularlypreferably 6 to 30 mm, and an outer diameter of 6 to 44 mm,particularly preferably 8 to 32 mm. The inner layer 1preferably has a thickness of 0.02 to 1.0 mm, particularlypreferably 0.05 to 0.6 mm. The low fuel permeability layer2 preferably has a thickness of 0.02 to 0.8 mm, particularlypreferably 0.05 to 0.6 mm. Further, when an outer layer isformed, the outer layer generally has a thickness of 0.3 to 1.5mm, preferably 0.5 to 1.0 mm.[0035] The inventive automotive fuel hose may preferablybe used as a transportation hose for automotive fuel such asgasoline, alcohol-containing gasoline, diesel fuel, com-pressed natural gas (CNG), liquefied petroleum gas (LPG),but is not limited thereto. The inventive automotive fuelhose may be used as a transportation hose for methanol,hydrogen, dimethylether (DME) or the like for applicationssuch as for fuel cell-powered vehicles.

Mar. 4, 20043

[0036] Next, an explanation will be given to Examples andComparative Examples.[0037] Prior to the explanation of Examples and Com-parative Examples, the ingredients employed therein will bedescribed below.[0038] ETFE[0039] The impact strength was 150 Jim at _400 C.[0040] Electrically Conductive ETFE[0041] An electrically conductive ethylene-tetrafiuoroeth-ylene copolymer (ETFE) was prepared by blending 15 wt %of electrically conductive carbon black (Denka black avail-able from Denki Kagaku Kogyo KKof Tokyo, Japan) inETFE. The thus obtained electrically conductive ETFE hadan impact strength of 75 Jim at _400 C.[0042] Epoxy-Modified ETFE[0043] Epoxy-modified ETFE was prepared by blending 2parts by weight Gust abbreviated as 'parts', hereinafter) ofglycidyl methacrylate and 2 parts of dicumyl peroxiderelative to 100 parts of ETFE and melt-kneading the result-ant mixture by means of a twin screw extruder. The thusobtained epoxy-modified ETFE had an impact strength of 60Jim at _400 C.[0044] Hydroxy-Modified ETFE[0045] Hydroxy-modified ETFE was prepared by blend-ing 1.5 parts ofvinylmethoxy silane and 1.5 parts of dicumylperoxide relative to 100 parts of ETFE and melt-kneadingthe resultant mixture by means of a twin screw extruder. Thethus obtained hydroxy-modified ETFE had an impactstrength of 55 Jim at _400 C.[0046] Carboxylic Anhydride-Modified ETFE[0047] Carboxylic anhydride-modified ETFE was pre-pared by blending 1.5 parts of maleic anhydride and 0.2parts of dicumyl peroxide relative to 100 parts of ETFE andmelt-kneading the resultant mixture by means of a twinscrew extruder. The thus obtained carboxylic anhydride-modified ETFE had an impact strength of 62 Jim at _400 C.[0048] Electrically Conductive Epoxy-Modified ETFE[0049] Electrically conductive epoxy-modified ETFE wasprepared by blending 15 parts of electrically conductivecarbon black (Denka black available from Denki KagakuKogyo KK of Tokyo, Japan) relative to 100 parts of theepoxy-modified ETFE and melt-kneading the resultant mix-ture by means of a twin screw extruder. The thus obtainedelectrically conductive epoxy-modified ETFE had an impactstrength of 49 Jim at _400 C.[0050] Acrylate-Modified ETFE[0051] Acrylate-modified ETFE was prepared by blending2 parts of methyl acrylate and 2 parts of dicumyl peroxiderelative to 100 parts of ETFE and melt-kneading the result-ant mixture by means of a twin screw extruder. The thusobtained acrylate-modified ETFE had an impact strength of45 Jim at _400 C.[0052] Amino-Modified ETFE[0053] Amino-modified ETFE was prepared by blending 2parts of arylamine and 1.8 parts of dicumyl peroxide relativeto 100 parts of ETFE and melt-kneading the resultant


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mixture by means of a twin screw extruder. The thusobtained amino-modified ETFE had an impact strength of 50Jim at _40 C.[0054] Carboxylate-Modified ETFE[0055] Carboxylate-modified ETFE was prepared byreacting perfiuoro-(9,9-dihydro-2,5-bistrifiuoromethyl-3,6-dioxa-8-nonenoic acid), tetrafiuoroethylene, and ethylene,and adding zinc acetate, and then melt-kneading the result-ant mixture by means of a twin screw extruder. The thusobtained carboxylate-modified ETFE had an impact strengthof 21 Jim at _40 C.[0056] Carboxy-Modified ETFE[0057] Carboxy-modified ETFE was prepared by blending1.5 parts of maleic acid and 0.2 parts of dicumyl peroxiderelative to 100 parts of ETFE and melt-kneading the result-ant mixture by means of a twin screw extruder. The thusobtained carboxy-modified ETFE had an impact strength of28 Jim at _40 C.[0058] Epoxy-Modified THV[0059] Epoxy-modified THV was prepared by blending 4parts of glycidyl methacrylate and 2 parts of dicumylperoxide relative to 100 parts of THV and melt-kneading theresultant mixture by means of a twin screw extruder. Thethus obtained epoxy-modified THV had an impact strengthof 60 Jim at _40 C.[0060] PBN[0061] A condensation product (TQB-OT available fromTeijin Chemicals Ltd.) of tetramethylene glycol and 2,6-naphthalenedicarboxylic acid.[0062] PBN-Ether[0063] A PBN-ether was obtained by copolymerizing 10parts of polytetramethylene glycol as an ether segmentrelative to 100 parts of PBN.[0064] PBN-Ester[0065] A PBN-ester was obtained by copolymerizing 10parts of polycaprolactone as an ester segment relative to 100parts of PBN.[0066] PBN-Fatty Acid[0067] PBN-fatty acid was obtained by copolymerizingdicarboxylic acid of fatty acid (PRIPOL 1008 available fromUniqema of Gouda, the Netherlands) with PBN in such amanner that dicarboxylic acid of fatty acid was present at 3mol % based upon the total amount.[0068] TPEE[0069] Ester thermoplastic elastomer (HYTREL 5577available from DuPont- Toray Co., Ltd. of Tokyo, Japan.)[0070] AD (1)[0071] A mixture obtained by blending ETFE, PBN andethyleneglycidyl methacrylate in a weight ratio of 5:5: 1.Themixture had an impact strength of 26 Jim at _40 C.[0072] AD (2)[0073] A mixture obtained by blending PA12, PBN and athermoplastic polyurethane in a weight ratio of 4:4: 1.

Mar. 4, 20044

EXAMPLE 1[0074] Each extruder for an inner layer, a low fuel per-meability layer and an outer layer was prepared, respec-tively. Each material was extruded by each extruder, and wascombined in a die, and then passed through a sizing die,whereby a low fuel permeability PBN layer was formeddirectly on an outer peripheral surface of an inner epoxy-modified ETFE layer, and further an outer TPEE layer wasformed directly on an outer peripheral surface of the low fuelpermeability PBN layer. Thus, a fuel hose was producedwhich has an inner diameter of 6 mm and an outer diameterof 8 mm.

EXAMPLES 2 TO 12 AND COMPARATIVEEXAMPLES 1 TO 6

[0075] Fuel hoses were produced in substantially the samemanner as in Example 1, except that inner layer materials,low fuel permeability layer materials and outer layer mate-rials shown in Tables 1 to 3 were employed. The formationof the inner layer having the double-layer structure isachieved by simultaneously extruding an inner sublayermaterial and an outer sublayer material from separateextruders and combining the resulting sublayers in a die. Forformation of an adhesive layer, another extruder was utilizedand an adhesive layer material was simultaneously extrudedwith each material and was combined in a die and passedthrough a sizing die.[0076] The properties of the fuel hoses of Examples andComparative Examples were evaluated in the followingmanner. The results are shown in Tables 1 to 3.[0077] Gasoline Permeability[0078] Opposite end portions of a 10 m long fuel hose(having an inner diameter of 6 mm) were each expanded toan inner diameter of 10 mm by means of a cone-shaped jig.Then, two metal pipes were prepared which each had anouter diameter of 8 mm with two bulged portions eachhaving an outer diameter of 10 mm and with each one endthereof having a rounded outer periphery. These metal pipeswere respectively press-fitted into opposite end portions ofthe hose. A blind cap was threadingly attached to one of themetal pipes, and a metal valve was attached to the othermetal pipe. Thereafter, regular gasoline (containing 10 vol %ethanol) was supplied into the fuel hose through the metalvalve, and the fuel hose was sealed. The fuel hose wasallowed to stand at 40 C. for 3000 hours (the regulargasoline was changed every week). Then, fuel permeationwas measured for three days on the basis of a DiurnalBreathing Loss (DBL) pattern by the Sealed Housing forEvaporative Detection (SHED) method in accordance withCalifornia Air Resources Board (CARB). Then, fuel perme-ation per meter of the hose was determined on a day whenthe maximum fuel permeation was detected. In Tables 1 to3, the notation "


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low fuel permeability layer, and a symbol x indicates that thelow fuel permeability layer was cracked.[0081] Adhesion[0082] The fuel hoses were each longitudinally cut intofour strips. By using one of the strips, a peel force (N/cm)required for separating the inner layer from the low fuelpermeability layer was determined. Separetely, fuel hoseswere each filled with a fuel (prepared by blending 10 vol %of ethanol in 90 vol % of Fuel C (50% by volume oftoluene+50% by volume of isooctane) and allowed to standstill at 60 C. for one week. Adhesion (N/cm) between theinner layer and the low fuel permeability layer was deter-mined in the same manner as described above.

Mar. 4, 20045[0083] Impact Resistance[0084] Soon after each fuel hose was allowed to stand at_40 C. for 4 hours, a drop-weight test was conducted inconformity with JASO M317 in such a manner that a fallingweight (round rod having a diameter of 32 mm and 450 gand both ends thereof with 16 mm radius of curvature,respectively) was dropped from the height of 305 mm ontoeach fuel hose. Then, each hose was cut into halves longi-tudinally, and occurrence of abnormality was visually evalu-ated on both inner and outer sides of each fuel hose. InTables 1 to 3, a symbol 0 indicates that no cracking wasobserved on the low fuel permeability layer, and a symbol xindicates that the low fuel permeability layer was cracked.

TABLE 1Exam le

2 3 4 5Inner layer Epoxy- Hydroxy- Carboxylic Epoxy- Epoxy- Epoxy-

modified modified anhydride- modified modified modifiedETFE ETFE modified ETFE ETFE ETFE

ETFELow fuel per- PBN PBN PBN PBN- PBN- PBN-fattymeability layer ether ether acidOuter layer TPEE TPEE TPEE TPEE TPEE TPEEThickness (mm)Inner layer 0.2 0.2 0.2 0.2 0.2 0.2Low fuel per- 0.1 0.1 0.1 0.1 0.1 0.1meability layerOuter layer 0.7 0.7 0.7 0.7 0.7 0.7Gasoline permea-


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TABLE 2-continuedExam le

7 8 9 10 11 12Low fuel per- 0.1 0.1 0.1 0.1 0.1 0.1meability layerAdhesive layer 0.2Outer layer 0.7 0.7 0.5 0.7 0.7 0.7Gasoline permea-


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ability and impact resistance. The fuel hose of ComparativeExample 5, whose low fuel permeability layer was formedby PET, was inferior in low fuel permeability and hydrolysisresistance. Further, compared with Example 2, which has thesame construction except that the low fuel permeabilitylayer of Example 2 was formed by PEN, the fuel hose ofComparative Example 5 was inferior in adhesion both at aninitial stage and after being filled with fuel. The fuel hose ofComparative Example 6, whose low fuel permeability layeris formed by PET, was inferior in low fuel permeability andhydrolysis resistance. Still further, compared with Example3, which has the same construction except that the low fuelpermeability layer of Example 3 was formed by PEN, thefuel hose of Comparative Example 6 was inferior in adhe-sion both at an initial stage and after being filled with fuel.[0089] As described above, the inner layer of the inventiveautomotive fuel hose is formed by the fiuororesin having thefunctional group and the low fuel permeability layer isformed by the polyester resin having the naphthalene ring.Therefore, the functional group of the fiuororesin interactswith the terminal carboxyl group or the terminal hydroxylgroup of the polyester resin having the naphthalene ring, sothat the adhesion therebetween is enhanced. Therefore, theinter-layer adhesion between the inner layer and the lowpermeability layer is excellent and impact resistance isimproved. Further, since the low fuel permeability layer isformed by the polyester resin having the naphthalene ring,the inventive automotive hose is excellent in the low fuelpermeability and in hydrolysis resistance.[0090] When the impact strength of the fiuororesin havingthe functional group for forming the inner layer is not lessthan 30 11 m at _400 c., the impact resistance of the resultanthose is improved and the hose is more practicable as anautomotive fuel hose.[0091] When the low fuel permeability layer is formed byPEN or PEN, the PEN or the PEN can be extruded at ahigher temperature because each of the PEN or the PEN hasa high melting point, respectively, so that the adhesion withthe fiuororesin having the functional group for the innerlayer is further improved and the impact resistance of theresultant hose is improved.What is claimed is:1. An automotive fuel hose comprising: a tubular inner

layer comprising a fiuororesin having a functional group;and a low fuel permeability layer comprising a polyesterresin having a naphthalene ring; the inner layer in which fuelis adapted to fiow; the low fuel permeability layer beinglaminated onto the inner layer such that respective matinginterfaces contact each other.2. An automotive fuel hose as set forth in claim 1, wherein

the fiuororesin has impact strength of not less than 30 11 m at_400 C.3. An automotive fuel hose as set forth in claim 1, wherein

the polyester resin is either a polybutylene naphthalate or apolyethylene naphthalate.

Mar. 4, 20047

4. An automotive fuel hose as set forth in claim 2, whereinthe polyester resin is either a polybutylene naphthalate or apolyethylene naphthalate.5. An automotive fuel hose as set forth in claim 1, wherein

the functional group is at least one functional group selectedfrom the group consisting an epoxy group, a hydroxyl group,a carboxylic anhydride residual group, an acrylate group andan amino group.6. An automotive fuel hose as set forth in claim 2, wherein




the fiuororesin is either an ethylene-tetrafiuoroethylenecopolymer or a vinylidene fiuoride-tetrafiuoroethylene-hexafiuoropropylene copolymer.10. An automotive fuel hose as set forth in claim 2,

wherein the fiuororesin is either an ethylene-tetrafiuoroeth-ylene copolymer or a vinylidene fiuoride-tetrafiuoroethyl-ene-hexafiuoropropylene copolymer.11. An automotive fuel hose as set forth in claim 3,

wherein the fiuororesin is either an ethylene-tetrafiuoroeth-ylene copolymer or a vinylidene fiuoride-tetrafiuoroethyl-ene-hexafiuoropropylene copolymer.12. An automotive fuel hose as set forth in claim 4,wherein the fiuororesin is either an ethylene-tetrafiuoroeth-

ylene copolymer or a vinylidene fiuoride-tetrafiuoroethyl-ene-hexafiuoropropylene copolymer.13. An automotive fuel hose as set forth in claim 5,

wherein the fiuororesin is either an ethylene-tetrafiuoroeth-ylene copolymer or a vinylidene fiuoride-tetrafiuoroethyl-ene-hexafiuoropropylene copolymer.14. An automotive fuel hose as set forth in claim 6,

wherein the fiuororesin is either an ethylene-tetrafiuoroeth-ylene copolymer or a vinylidene fiuoride-tetrafiuoroethyl-ene-hexafiuoropropylene copolymer.15. An automotive fuel hose as set forth in claim 7,wherein the fiuororesin is either an ethylene-tetrafiuoroeth-

ylene copolymer or a vinylidene fiuoride-tetrafiuoroethyl-ene-hexafiuoropropylene copolymer.16. An automotive fuel hose as set forth in claim 8,wherein the fiuororesin is either an ethylene-tetrafiuoroeth-

ylene copolymer or a vinylidene fiuoride-tetrafiuoroethyl-ene-hexafiuoropropylene copolymer.

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Automotive Fuel Hose-4 Mar 2004

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Transcript of Automotive Fuel Hose-4 Mar 2004