Fuel filler pipe

Abstract

Provided is a fuel filler pipe consisting of: an internal layer containing a fluorine-containing copolymer that has a carbonyl group-containing group and has a melting point of 250°C or less; an intermediate layer containing a fluorine-free copolymer having an unit based on ethylene and a unit based on a vinyl alcohol; and an outer layer containing a polyolefin. The internal layer, the intermediate layer, and the outer layer are directly laminated in this order. The outer layer is a layer containing a polyolefin having a unit based on an acid anhydride, or is a layer obtained by directly laminating a layer containing a polyolefin having a unit based on an acid anhydride and a layer containing a polyolefin not having a unit based on an acid anhydride.

Description

[Technical Field]

[0001] This invention relates to a fuel filler pipe. [Background technology]

[0002] Fuel filler pipes are used to transport fuel from the fuel filler port to the gas tank. In recent years, from the perspective of saving gasoline consumption and improving engine performance, oxygenated gasoline blended with low-boiling-point alcohols such as methanol or ethanol, or ethers such as ethyl-t-butyl ether (ETBE), has come to be used as fuel.

[0003] Currently, from the perspective of preventing environmental pollution, strict exhaust gas regulations are in place, including measures to prevent leakage into the atmosphere due to the diffusion of volatile hydrocarbons through fuel filler pipe partitions. In the future, even stricter legal regulations may be imposed, potentially requiring further suppression of fuel permeating and evaporating through fuel filler pipe partitions.

[0004] Conventional single-layer tubes using polyethylene resins or polyamide resins, particularly polyamide 11, polyamide 12, polyamide 612, polyamide 1010, or polyamide 1012 which have excellent strength, toughness, chemical resistance, and flexibility, do not adequately prevent permeation to oxygenated gasoline, and there is a need to improve the permeation prevention properties, especially for gasoline blended with alcohol.

[0005] U.S. Patent No. 8,133,561 describes a multilayer composite material having an inner layer selected from the group consisting of fluoropolymer molding compositions and polyolefin molding compositions, an adhesive layer containing polyamide, and a barrier layer containing an ethylene-vinyl alcohol copolymer (EVOH) molding composition, and a fuel line using this multilayer composite material. [Overview of the project] [Problems that the invention aims to solve]

[0006] Problems may arise when a polyamide adhesive is used as an adhesive layer between the barrier layer containing the EVOH molding composition and the inner layer of the fluororesin molding composition. For example, fuel may permeate the inner layer, causing oligomers, monomers, and plasticizers of compounds contained in the polyamide adhesive to dissolve into the fuel, potentially clogging the filter before the engine. If the filter before the engine becomes clogged, the supply of fuel to the engine will be cut off.

[0007] The present invention aims to provide a fuel filler pipe that exhibits excellent fuel shielding properties, excellent resistance to thermal aging, excellent interlayer adhesion, and excellent conductivity. [Means for solving the problem]

[0008] (1) One aspect of the present invention is a fuel filler pipe comprising only an inner layer containing a fluorine-containing copolymer having units based on tetrafluoroethylene and units based on ethylene, having carbonyl group-containing groups and having a melting point of 250°C or less; an intermediate layer containing a non-fluorine copolymer having units based on ethylene and units based on vinyl alcohol; and an outer layer containing a polyolefin, wherein the inner layer, the intermediate layer, and the outer layer are directly laminated in this order, and the outer layer is a layer containing a polyolefin having units based on acid anhydride, or a layer containing a polyolefin having units based on acid anhydride and a layer containing a polyolefin not having units based on acid anhydride are directly laminated. (2) In another embodiment of the fuel filler pipe described above, the carbonyl group-containing group in the fluorine-containing copolymer is a carbonyl group-containing group derived from a unit based on a monomer having a carbonyl group-containing group. (3) In another embodiment of the fuel filler pipe described above, the carbonyl group-containing group of the fluorine-containing copolymer is an acid anhydride group derived from a unit based on a monomer having an acid anhydride group. (4) In another embodiment of the fuel filler pipe described above, the inner layer contains 80 to 100% by mass of the fluorine-containing copolymer, the intermediate layer contains 80 to 100% by mass of the non-fluorine copolymer, and the outer layer contains 80 to 100% by mass of the polyolefin. (5) In another embodiment of the fuel filler pipe described above, the inner layer includes a conductive filler. (6) In the embodiment described in (5) above, the surface resistivity of the inner layer is 10 5 It may be less than or equal to Ω / sq. (7) In another embodiment of the fuel filler pipe described above, the surface resistivity of the inner layer is 10 5 It is less than or equal to Ω / sq. (8) In another embodiment of the fuel filler pipe described above, in the intermediate layer, the non-fluorine copolymer contains 25 to 50 mol% of ethylene-based units relative to the total units constituting the non-fluorine copolymer. (9) In another embodiment of the fuel filler pipe described above, in the intermediate layer, the vinyl alcohol-based units constituting the non-fluorine copolymer are obtained by saponifying 99% or more of the vinyl acetate-based units. (10) In another embodiment of the fuel filler pipe described above, the sum of the thicknesses of the inner layer, the intermediate layer, and the outer layer is 1.0 to 20.0 mm. (11) In the embodiment described in (10) above, the thickness of the inner layer may be 10 to 30% of the thickness of the outer layer. (12) In the embodiment described in (11) above, the thickness of the intermediate layer may be 10 to 30% of the thickness of the outer layer. (13) In another embodiment of the fuel filler pipe described above, ester bonds are present at both the first interface between the inner layer and the intermediate layer, and the second interface between the intermediate layer and the outer layer. (14) In the embodiment described in (13) above, the ester bond may be an ester bond formed from an acid anhydride group and a hydroxyl group. (15) In another aspect of the above fuel filler pipe, the peel strength at both the first interface between the inner layer and the intermediate layer and the second interface between the intermediate layer and the outer layer is 30 N / cm or more. (16) In another aspect of the above fuel filler pipe, the fuel permeation coefficient of the inner layer, determined by the following cup method using CE1 at 60 °C, which is a test fuel of isooctane: toluene: ethanol (volume ratio) = 45:45:10, is 6.0 g·mm / (m 2 ·24 h) or less. (Cup method) A test piece with a thickness of 100 μm is prepared. In accordance with the cup method specified in JIS Z 0208-1976, 4.6 g of the specified test fuel is placed in a cup with a permeation area of 11.33 cm 2 , covered with the test piece at the top of the cup, and after holding at 60 °C for 10 days, the mass reduction amount is recorded, and the fuel permeation coefficient of the polymer is determined from the following formula. s Fuel permeation coefficient = mass reduction amount (g) × thickness of test piece (mm) / (permeation area (m 2 ) × permeation days) (17) In another aspect of the above fuel filler pipe, after enclosing CE1 and exposing it at a temperature of 40 °C for 1000 hours, the surface resistivity of the inner layer is 10 5 Ω / sq. or less. (18) In another aspect of the above fuel filler pipe, the peel strength at both the first interface between the inner layer and the intermediate layer and the second interface between the intermediate layer and the outer layer is 40 N / cm or more. (19) In another aspect of the above fuel filler pipe, the inner layer has a residual rate of 75% or more of the initial tensile fracture strength of the tensile fracture strength after being exposed to an ambient temperature of 200 °C for 1000 hours. (20) In another aspect of the above fuel filler pipe, the inner layer has a residual rate of 75% or more of the initial tensile fracture elongation of the tensile fracture elongation after being exposed to an ambient temperature of 200 °C for 1000 hours. s (21) In another aspect of the above fuel filler pipe, the inner layer has a residual rate of 70% or more of the initial tensile fracture strength of the tensile fracture strength after being exposed to an ambient temperature of 220 °C for 1000 hours. In another aspect of the fuel filler pipe, the inner layer has a residual ratio of the tensile elongation at break after exposure to an ambient temperature of 220°C for 1000 hours with respect to the initial tensile elongation at break of 65% or more.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a fuel filler pipe excellent in fuel shielding properties, excellent in resistance to heat aging, excellent in interlayer adhesion, and excellent in conductivity.

Modes for Carrying Out the Invention

[0010] In the present invention, the following definitions of terms are used. "Melting point" is the temperature corresponding to the maximum value of the melting peak measured by differential scanning calorimetry (DSC). "Unit based on a monomer" is a general term for an atomic group directly formed by the polymerization of one molecule of a monomer and an atomic group obtained by chemically converting a part of the atomic group. In this specification, the unit based on a monomer is also simply referred to as a monomer unit. For example, the unit based on TFE is also referred to as a TFE unit. "Monomer" means a compound having a polymerizable carbon-carbon double bond. "Conductive filler" means a filler for a resin that has conductivity. "Aspect ratio" means the value obtained by dividing the length of the conductive filler by the thickness of the conductive filler. "~" indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value. "TFE" means tetrafluoroethylene. "TFE unit" means a unit based on tetrafluoroethylene. "E unit" means a unit based on ethylene. "P unit" means a unit based on propylene. "VOH" means vinyl alcohol. "VOH unit" means a unit based on vinyl alcohol. "Alkali metals" refers to metals located in Group 1 of the Periodic Table (IUPAC Periodic Table of Elements). Specifically, alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). "Alkaline earth metals" refers to metals located in Group 2 of the Periodic Table (IUPAC Table of Elements). Specifically, alkaline earth metals include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

[0011] [Fuel filler pipe] The fuel filler pipe of the present invention consists only of an inner layer containing a fluorine-containing copolymer, an intermediate layer containing a non-fluorine copolymer, and an outer layer containing a polyolefin.

[0012] <Inner layer> The inner layer is a layer containing a fluorine-containing copolymer. The fluorine-containing copolymer contained in the inner layer is a fluorine-containing copolymer having TFE units and E units. The above fluorine-containing copolymer has a carbonyl group-containing group. The above-mentioned fluorine-containing copolymer has a melting point of 250°C or lower. Hereinafter, the above-mentioned fluorine-containing copolymer, that is, "a fluorine-containing copolymer having TFE units and E units, having a carbonyl group-containing group, and having a melting point of 250°C or less," will also be referred to as "ETFE-based copolymer." The above-mentioned inner layer may be a layer comprising an inner layer-forming composition containing the above-mentioned ETFE-based copolymer.

[0013] Examples of the carbonyl group-containing groups mentioned above include groups having carbonyl groups between carbon atoms of a hydrocarbon group, carbonate groups, carboxyl groups, haloformyl groups, alkoxycarbonyl groups, and acid anhydride groups.

[0014] Examples of hydrocarbon groups having carbonyl groups between carbon atoms include alkylene groups having 2 to 8 carbon atoms. The number of carbon atoms in the alkylene group having 2 to 8 carbon atoms is the number of carbon atoms excluding those constituting the carbonyl group. The alkylene group may be linear or branched. The above haloformyl group is represented as -C(=O)-X, where X represents a halogen atom. Examples of the above halogen atom include a fluorine atom and a chlorine atom, with a fluorine atom being preferred. The alkoxy group in the above-mentioned alkoxycarbonyl group may be linear or branched. The alkoxy group is preferably a carbon-1 to carbon-8 alkoxy group, and more preferably a methoxy group or an ethoxy group. The above acid anhydride group is preferably an unsaturated carboxylic acid anhydride group, more preferably a dicarboxylic acid anhydride group, and even more preferably a dicarboxylic acid anhydride group bonded to a cyclic hydrocarbon.

[0015] As the above ETFE-based copolymer, a copolymer containing TFE units (a), E units (b), and AHM units (c) (hereinafter also referred to as "ETFE-AHM-based copolymer") is preferred. Here, "AHM" means at least one functional monomer selected from the group consisting of itaconic anhydride, itaconic acid, citraconic anhydride, and citraconic acid, and "AHM unit" means a unit based on AHM.

[0016] In the above ETFE-AHM copolymer, the molar ratio (Ma / Mb) of TFE units (a) to E units (b) is preferably 20 / 80 to 80 / 20, and more preferably 50 / 50 to 70 / 30. Here, Ma and Mb represent the number of moles of TFE units (a) and E units (b) in the above ETFE-AHM copolymer, respectively. When Ma / Mb is above the lower limit of the above range, the heat resistance, weather resistance, chemical resistance, gas barrier properties, and liquid barrier properties of the above ETFE-AHM copolymer are higher, and when Ma / Mb is below the upper limit of the above range, the mechanical strength and melt moldability of the above ETFE-AHM copolymer are higher. When Ma / Mb is within the above range, the heat resistance, weather resistance, chemical resistance, gas barrier properties, liquid barrier properties, mechanical strength, and melt moldability of the above ETFE-AHM copolymer are superior.

[0017] In the above ETFE-AHM copolymer, the molar ratio (Mc / (Ma+Mb)) of the sum of AHM units (c), TFE units (a), and E units (b) is preferably 1 / 10000 to 5 / 100, more preferably 1 / 1000 to 5 / 100, even more preferably 3 / 2000 to 3 / 100, and even more preferably 3 / 1000 to 3 / 100. Here, Ma, Mb, and Mc are the molar ratios of TFE units (a), E units (b), and AHM units (c) in the above ETFE-AHM copolymer, respectively. This refers to the number of layers. If Mc / (Ma+Mb) is greater than or equal to the lower limit of the above range, the interlayer adhesion between the inner layer containing the ETFE-AHM copolymer and the intermediate layer containing the non-fluorine copolymer becomes higher, and if it is less than or equal to the upper limit of the above range, the liquid barrier properties of the inner layer containing the ETFE-AHM copolymer become higher. If Mc / (Ma+Mb) is within the above range, the inner layer containing the ETFE-AHM copolymer exhibits superior interlayer adhesion and liquid barrier properties with respect to the intermediate layer containing the non-fluorine copolymer.

[0018] As the above ETFE copolymer, in addition to the ETF unit (a), E unit (b) and AHM unit (c), a copolymer containing a repeating unit (d) based on other fluorine-containing monomers (excluding TFE) (hereinafter, also referred to as "ETFE-AHM-OTHER copolymer") is more preferable.

[0019] Examples of the above other fluorine-containing monomers (excluding TFE) include chlorotrifluoroethylene (hereinafter, also referred to as "CTFE"), CH2=CX(CF2) n Y (where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer of 2 to 8), vinylidene fluoride (hereinafter, also referred to as "VDF"), and fluoroolefins having a hydrogen atom in an unsaturated group such as vinyl fluoride; fluoroolefins having no hydrogen atom in an unsaturated group such as hexafluoropropylene (hereinafter, also referred to as "HFP") (excluding TFE); perfluoro(alkyl vinyl ether) such as perfluoro(methyl vinyl ether), perfluoro(propyl vinyl ether) (hereinafter, also referred to as "PPVE") and perfluoro(butyl vinyl ether); and fluorine-containing alkyl vinyl ethers having a hydrogen atom such as 2,2,2-trifluoroethyl trifluorovinyl ether. The above other fluorine-containing monomers may be used alone or in combination of two or more.

[0020] Examples of the above other fluorine-containing monomers (excluding TFE) include CH2=CX(CF2) n Y (where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer of 2 to 8), VDF, HFP and at least one selected from the group consisting of PPVE are preferable, and CH2=CX(CF2) n Y (where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer of 2 to 8) is more preferable.

[0021] CH2=CX(CF2) nIn Y (where X and Y are independently hydrogen atoms or fluorine atoms, and n is an integer from 2 to 8), an integer n = 2 to 4 is preferred. The above ETFE-AHM-OTHER copolymer has a unit (d) based on the above other fluorine-containing monomers (excluding TFE), CH2=CX(CF2) n When a unit based on Y (where X and Y are independently hydrogen atoms or fluorine atoms, and n is an integer between 2 and 4) is included, the inner layer containing the above ETFE-AHM-OTHER copolymer exhibits superior liquid barrier properties and crack resistance. CH2=CX(CF2) n Specific examples of Y (where X and Y are independently hydrogen atoms or fluorine atoms, and n is an integer between 2 and 8) include CH2=CF(CF2)2F, CH2=CF(CF2)3F, CH2=CF(CF2)4F, CH2=CF(CF2)2H, CH2=CF(CF2)3H, CH2=CF(CF2)4H, CH2=CH(CF2)2F, CH2=CH(CF2)3F, CH2=CH(CF2)4F, CH2=CH(CF2)2H, CH2=CH(CF2)3H, and CH2=CH(CF2)4H. CH2=CX(CF2) n Y (where X and Y are independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8) is preferably at least one selected from the group consisting of CH2=CF(CF2)2F, CH2=CH(CF2)2F, CH2=CH(CF2)2H, and CH2=CF(CF2)2H, more preferably any one selected from the group consisting of CH2=CF(CF2)2F, CH2=CH(CF2)2F, CH2=CH(CF2)2H, and CH2=CF(CF2)2H, and even more preferably CH2=CH(CF2)2F.

[0022] In the above ETFE-AHM-OTHER copolymer, the content of repeating units (d) based on the above other fluorine-containing monomers (excluding TFE) is preferably 0.1 to 20 mol%, more preferably 0.5 to 15 mol%, and even more preferably 0.5 to 10 mol% relative to the total repeating units in the above ETFE-AHM-OTHER copolymer. When the content of repeating units (d) based on the above other fluorine-containing monomers (excluding TFE) is within the above range, the inner layer containing the above ETFE-AHM-OTHER copolymer exhibits superior crack resistance.

[0023] The melt flow rate (hereinafter also referred to as "MFR") of the above ETFE copolymer is preferably 0.1 to 1000 g / 10 min, and more preferably 1.0 to 100 g / 10 min. When the MFR of the ETFE copolymer is within the above range, the moldability of the ETFE copolymer is better. The above MFR of the ETFE copolymer was measured in accordance with ASTM D3159 under conditions of a temperature of 297°C and a load of 49 N.

[0024] The method for producing the above ETFE copolymer is not particularly limited, but a polymerization method using a radical polymerization initiator is preferred. Examples of the polymerization methods include bulk polymerization; solution polymerization using organic solvents such as fluorinated hydrocarbons, chlorinated hydrocarbons, fluorinated chlorinated hydrocarbons, alcohols, or hydrocarbons; suspension polymerization using an aqueous medium and, if necessary, a suitable organic solvent; and emulsion polymerization using an aqueous medium and an emulsifier, with solution polymerization being preferred.

[0025] The temperature at which the half-life of the above radical polymerization initiator is 10 hours is preferably 0°C to 100°C, and more preferably 20°C to 90°C. Examples of the radical polymerization initiators mentioned above include azo compounds such as azobisisobutyronitrile; non-fluorinated diacyl peroxides such as isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide and lauroyl peroxide; peroxy dicarbonates such as diisopropyl peroxy dicarbonate; peroxyesters such as tert-butyl peroxypivalate, tert-butyl peroxyisobutyrate and tert-butyl peroxyacetate; (Z(CF2) p Examples include fluorinated diacyl peroxides such as COO)2 (where Z is a hydrogen atom, a fluorine atom, or a chlorine atom, and p is an integer from 1 to 10); and inorganic peroxides such as potassium persulfate, sodium persulfate, and ammonium persulfate.

[0026] In the above-described method for producing the ETFE copolymer, a chain transfer agent may be used to control the MFR of the ETFE copolymer. Examples of the above-mentioned chain transfer agents include alcohols such as methanol and ethanol; chlorofluorohydrocarbons such as 1,3-dichloro-1,1,2,2,3-pentafluoropropane and 1,1-dichloro-1-fluoroethane; and hydrocarbons such as pentane, hexane, and cyclohexane. It is preferable that the above-mentioned chain transfer agent has a functional group such as an ester bond, a carbonate bond, a hydroxyl group, a carboxyl group, or a carbonyl fluoride group, because this introduces terminal groups that interact with the non-fluorine copolymer contained in the intermediate layer into the ETFE copolymer. Examples of the above-mentioned chain transfer agents having a functional group include acetic acid, acetic anhydride, methyl acetate, ethylene glycol, and propylene glycol.

[0027] In the above method for producing the ETFE copolymer, the polymerization conditions are not particularly limited. The polymerization temperature in the above method for producing the ETFE copolymer is preferably 0 to 100°C, and more preferably 20 to 90°C. The polymerization pressure in the above method for producing the ETFE copolymer is preferably 0.1 to 10 MPa, and more preferably 0.5 to 3 MPa. The polymerization time in the above method for producing the ETFE copolymer is preferably 1 to 30 hours. When the above ETFE-AHM copolymer is produced by solution polymerization, the concentration of AHM is preferably 0.01 to 5 mol%, more preferably 0.1 to 3 mol%, and even more preferably 0.1 to 1 mol%, relative to the total monomer. When the AHM concentration is below the upper limit of the above range, the polymerization rate tends to improve. When the AHM concentration is within the above range, the polymerization rate during production is improved, and the inner layer containing the produced ETFE-AHM copolymer exhibits superior interlayer adhesion with the intermediate layer. During polymerization, as AHM is consumed during polymerization, it is preferable to continuously or intermittently supply the consumed amount to the polymerization tank to maintain the AHM concentration within the above range.

[0028] The content of units based on monomers having carbonyl group-containing groups (hereinafter also referred to as "carbonyl group-containing units") in the above ETFE copolymer is preferably 0.05 to 20 mol%, more preferably 0.05 to 10 mol%, and even more preferably 0.1 to 5 mol%, relative to the total number of moles of units constituting the above ETFE copolymer. When the content of the carbonyl group-containing units is within the above range, the interlayer adhesion between the inner layer and the intermediate layer is further improved, the heat resistance of the ETFE copolymer is further improved, and peeling, discoloration, foaming, and elution due to decomposition during high-temperature processing, as well as decomposition during high-temperature use, are less likely to occur.

[0029] The melting point of the above ETFE copolymer is 250°C or lower, preferably between 150°C and 250°C, and more preferably between 180°C and 220°C. If the melting point of the above ETFE copolymer is above 250°C, the molding temperature cannot be lowered. If the melting point of the above ETFE copolymer is above the lower limit of the above range, the above ETFE copolymer has superior heat resistance.

[0030] The inner layer described above may contain other components besides the ETFE copolymer described above. Other components mentioned above include, for example, polymers other than the ETFE copolymer. Other polymers other than the ETFE copolymer include, for example, melt-mold fluorine-containing polymers other than ETFE copolymers and thermoplastic resins other than fluorine-containing polymers. Examples of fluorine-containing polymers that can be melt-molded other than the ETFE-based copolymers mentioned above include perfluoroalkoxyalkanes (hereinafter also referred to as "PFA"), ethylene-tetrafluoroethylene copolymers (excluding the ETFE-based polymers mentioned above) (hereinafter also referred to as "cETFE"), polyvinylidene fluoride (hereinafter also referred to as "PVDF"), and ethylene-chlorotrifluoroethylene copolymers (hereinafter also referred to as "ECTFE"). Examples of thermoplastic resins other than the fluorine-containing polymers mentioned above include thermoplastic polyimides, polyarylates, and polysulfones. Furthermore, the above-mentioned other components may include additives such as heat stabilizers, fillers, pigments, or ultraviolet absorbers.

[0031] The content of the ETFE copolymer in the inner layer is preferably 80 to 100% by mass, and more preferably 90 to 100% by mass, relative to the total mass of the inner layer.

[0032] The inner layer described above preferably further contains a conductive filler. Conductivity refers to the electrical properties of a material that prevent the accumulation of static electricity that could occur when a flammable fluid, such as gasoline, comes into continuous contact with an insulator, such as resin. This prevents the generation of sparks caused by static electricity during the transport of fluids such as fuel. Conductive fillers encompass all fillers added to resins to impart conductive properties, including, for example, granular fillers, flake fillers, and fibrous fillers. Examples of the granular fillers mentioned above include carbon black and graphite. Examples of the flake-shaped fillers mentioned above include aluminum flakes, nickel flakes, and nickel-coated mica. Examples of the fibrous fillers mentioned above include carbon nanotubes, carbon nanofibers, carbon fibers, carbon-coated ceramic fibers, carbon whiskers, and metal fibers such as aluminum fibers, copper fibers, brass fibers, and stainless steel fibers. Carbon black is preferred as the conductive filler mentioned above. The carbon blacks mentioned above are not particularly limited and include all carbon blacks commonly used to impart conductivity. Examples of the carbon blacks mentioned above include acetylene black obtained by the complete combustion of acetylene gas, Ketjen black produced by furnace-type incomplete combustion using crude oil as a raw material, oil black, naphthalene black, thermal black, lamp black, channel black, roll black, and disc black.

[0033] Furthermore, various types of carbon powders with different properties such as average particle size, specific surface area, DBP oil absorption, and ash content are manufactured. The properties of the carbon black are not particularly limited, but those with a good chain structure and high aggregation density are preferred. The average particle size of the carbon black is preferably 500 nm or less, more preferably 5 to 100 nm, and even more preferably 10 to 70 nm. When the average particle size of the carbon black is 500 nm or less, the inner layer can achieve excellent conductivity with a smaller amount of added carbon black, and also exhibit better impact resistance. The specific surface area (BET method) of the above carbon black is 10m². 2 Preferably 300m / g or more 2 More preferably 500-1500m / g or more. 2 / g is even more preferable. The DBP (dibutyl phthalate) oil absorption of the above carbon black is preferably 50 mL / 100g or more, more preferably 100 mL / 100g or more, and even more preferably 300 mL / 100g or more. The above DBP oil absorption values ​​were measured by the method specified in ASTM D-2414. The ash content of the carbon black described above is preferably 0.5% by mass or less, and more preferably 0.3% by mass or less. The volatile content of the carbon black described above is preferably less than 1.0% by mass.

[0034] The conductive filler may be surface-treated with a surface treatment agent such as a titanate-based, aluminum-based, or silane-based agent. As the conductive filler mentioned above, it is also possible to use one that has been granulated to improve melt-mixing workability. The amount of conductive filler blended in the inner layer cannot be specified in general terms as it varies depending on the type of conductive filler, but from the viewpoint of balancing the conductivity of the inner layer, the mechanical strength of the inner layer, and the fluidity of the inner layer forming composition for forming the inner layer, 3 to 30 parts by mass per 100 parts by mass of ETFE copolymer contained in the inner layer is preferred. Furthermore, the amount of conductive filler added is such that the surface resistivity of the molded product obtained by melt-extruding the inner layer forming composition containing the conductive filler is 10, in order to provide sufficient antistatic performance to the fuel filler pipe of the present invention. 8 Preferably, the amount is less than or equal to Ω, and 10 6 It is more preferable that the amount is less than or equal to Ω. However, the addition of the conductive filler tends to reduce the strength of the inner layer and worsen the fluidity of the inner layer forming composition. Therefore, if the target conductivity can be achieved, it is preferable to use as little conductive filler as possible.

[0035] The surface resistivity of the above inner layer is 10 5 Preferably Ω / sq. or less, 10 4 A value of Ω / sq. or less is more preferable. The surface resistivity of the inner layer described above was measured in accordance with SAE J-2260.

[0036] <Middle class> The intermediate layer is a layer containing a non-fluorine copolymer. The non-fluorinated copolymer contained in the intermediate layer is a non-fluorinated copolymer having E units and VOH units. Hereinafter, the non-fluorinated copolymer used in this invention will also be referred to as "EVOH copolymer". The above-mentioned intermediate layer is formed by melt extrusion of an intermediate layer-forming composition containing the above-mentioned EVOH copolymer.

[0037] The above EVOH copolymer is preferably obtained by saponifying an ethylene-fatty acid vinyl copolymer. In this case, the degree of saponification is preferably 99% or higher, and more preferably 99.5% or higher. When the degree of saponification is 99% or higher, the gas barrier properties of the intermediate layer are further improved, as is the melt stability. The lower limit of the ethylene content of the above EVOH copolymer is preferably 25 mol% or more, more preferably 30 mol% or more, and even more preferably 33 mol% or more. The upper limit of the ethylene content of the above EVOH copolymer is preferably 50 mol% or less, more preferably 45 mol% or less, even more preferably 40 mol% or less, and even more preferably 37 mol% or less. Furthermore, the range of the ethylene content of the above EVOH copolymer is preferably 25 to 50 mol%, more preferably 25 to 45 mol%, even more preferably 30 to 40 mol%, and even more preferably 33 to 37 mol%. When the ethylene content of the above EVOH copolymer is 25 mol% or more, the thermal stability of the intermediate layer forming composition during melt extrusion is less likely to decrease, and gelation is also less likely to occur. Furthermore, when forming the intermediate layer with the above intermediate layer forming composition, streaks and fish eyes are less likely to occur. The above effects are particularly noticeable when the fuel filler pipe of the present invention is used at higher temperatures or speeds for longer periods than under general conditions. When the ethylene content of the above EVOH copolymer is 45 mol% or less, the gas barrier properties of the intermediate layer formed with the above intermediate layer forming composition are less likely to decrease, and the original properties of the above EVOH copolymer are more easily retained. The above-mentioned intermediate layer forming composition may contain, in addition to the EVOH copolymer, auxiliary materials such as heat stabilizers, gelling inhibitors, or antioxidants, and vinyl acetate due to the degree of saponification not being 100%. The content of the above-mentioned EVOH copolymer in the above-mentioned intermediate layer forming composition is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass, based on the total mass of the above-mentioned intermediate layer forming composition.

[0038] The lower limit of the MFR (measured in accordance with ASTM D1238 at a temperature of 190°C and a load of 2160g) of the above intermediate layer forming composition is preferably 0.1g / 10min or higher, more preferably 0.5g / 10min or higher, even more preferably 1g / 10min or higher, and even more preferably 1.5g / 10min or higher. The upper limit of the above MFR is preferably 50g / 10min or lower, more preferably 15g / 10min or lower, even more preferably 12g / 10min or lower, and even more preferably 10g / 10min or lower. Furthermore, the range of the above melt index is preferably 0.1 to 50g / 10min, more preferably 0.5 to 15g / 10min, even more preferably 1 to 12g / 10min, and even more preferably 1.5 to 10g / 10min. When the melt index is 0.1 g / 10 min or higher, when the fuel filler pipe of the present invention is used at high temperatures for a long period of time, fish eyes and streaks are less likely to occur when forming the intermediate layer with the intermediate layer forming composition, and the output of the intermediate layer forming composition, i.e., the amount of resin that can be extruded when the same energy is applied, is further improved. When the melt index is 50 g / 10 min or less, the mechanical strength of the intermediate layer formed with the intermediate layer forming composition is increased, improving its practicality, and the melt viscosity does not become too low during melt molding at high temperatures, making multilayer molding easier.

[0039] The above-mentioned intermediate layer forming composition preferably contains a boron compound from the viewpoint of improving thermal stability, particularly long-run performance at high temperatures. Examples of the boron compounds include boric acid and boric acid derivatives such as boric acid esters and borate salts. Examples of the boric acid include orthoboric acid, metaboric acid, and tetraboric acid. Examples of the boric acid esters include triethyl borate and trimethyl borate. Examples of the borate salts include sodium metaborate, sodium tetraborate, sodium pentaborate, borax, lithium borate, and potassium borate. Orthoboric acid (H3BO3; hereinafter also simply referred to as "boric acid"), borax, and their derivatives are preferred as they have a significant effect in improving the thermal stability of the intermediate layer and are inexpensive.

[0040] The lower limit of the boron compound content in the above-mentioned intermediate layer forming composition is preferably 100 ppm or more, more preferably 500 ppm or more, and even more preferably 1000 ppm or more, based on the total mass of the intermediate layer forming composition in terms of boric acid (H3BO3). The upper limit of the boron compound content in the above-mentioned intermediate layer forming composition is preferably 5000 ppm or less, more preferably 3000 ppm or less, and even more preferably 2000 ppm or less, based on the total mass of the intermediate layer forming composition in terms of boric acid (H3BO3). Furthermore, the range of the boron compound content in the above-mentioned intermediate layer forming composition is preferably 100 to 5000 ppm, more preferably 500 to 3000 ppm, and even more preferably 1000 to 2000 ppm, based on the total mass of the intermediate layer forming composition in terms of boric acid (H3BO3). When the boron compound content of the above-mentioned intermediate layer forming composition is 100 ppm or more in terms of boric acid (H3BO3) relative to the total mass of the intermediate layer forming composition, torque fluctuations during heating and melting of the intermediate layer forming composition are further suppressed, and melt extrudeability is improved. If the boron compound content of the above-mentioned intermediate layer forming composition is 5000 ppm or less in terms of boric acid (H3BO3) relative to the total mass of the intermediate layer forming composition, gelation due to localization of the boron compound is less likely to occur, fish eyes and gel do not form during melt molding, and moldability is improved.

[0041] Furthermore, from the viewpoint of preventing discoloration of the intermediate layer, the above-mentioned intermediate layer-forming composition preferably contains at least one selected from the group consisting of carboxylic acids and their salts. Examples of the carboxylic acids mentioned above include acetic acid and propionic acid, with acetic acid being preferred. Furthermore, among the carboxylic acids, monocarboxylic acids (such as acetic acid) with only one carboxyl group in the molecule are preferred over polycarboxylic acids (such as adipic acid or phthalic acid) with two or more carboxyl groups in the molecule. Polycarboxylic acids may crosslink the EVOH copolymer between molecules, potentially worsening its thermal stability.

[0042] The lower limit of the content of at least one substance selected from the group consisting of the carboxylic acid and its salts in the above-mentioned intermediate layer forming composition is preferably 100 ppm or more, more preferably 150 ppm or more, and even more preferably 200 ppm or more, based on the total mass of the intermediate layer forming composition in terms of carboxylic acid. The upper limit of the content of at least one substance selected from the group consisting of the carboxylic acid and its salts in the above-mentioned intermediate layer forming composition is preferably 1000 ppm or less, more preferably 500 ppm or less, and even more preferably 400 ppm or less, based on the total mass of the intermediate layer forming composition. Furthermore, the range of the content of at least one substance selected from the group consisting of the carboxylic acid and its salts in the above-mentioned intermediate layer forming composition is preferably 100 to 1000 ppm, more preferably 150 to 500 ppm, and even more preferably 200 to 400 ppm, based on the total mass of the intermediate layer forming composition. If the content of at least one selected from the group consisting of the above carboxylic acid and its salts in the above intermediate layer forming composition is 100 ppm or more relative to the total mass of the intermediate layer forming composition, the effect of preventing discoloration during melt molding of the intermediate layer will be more pronounced, and the intermediate layer will be less prone to yellowing. If the content of at least one selected from the group consisting of the above carboxylic acid and its salts in the above intermediate layer forming composition is 1000 ppm or less relative to the total mass of the intermediate layer forming composition, then the intermediate layer forming composition is less likely to gel during melt molding, especially during long melt molding periods, thereby suppressing the formation of fish eyes and gel, and eliminating the risk of appearance defects.

[0043] The above-mentioned intermediate layer forming composition preferably contains an alkali metal salt from the viewpoint of improving interlayer adhesion between the inner layer and the outer layer described later. Examples of alkali metals constituting the alkali metal salt mentioned above include lithium, sodium, and potassium, with potassium or sodium being preferred.

[0044] If the above borate is an alkali metal salt, examples of the alkali metal salt include sodium salts and potassium salts.

[0045] Examples of the alkali metal salts mentioned above include carboxylates, phosphates, and borates, with carboxylates being preferred, lactates or acetates being more preferred, and acetates being even more preferred.

[0046] The lower limit of the alkali metal salt content in the above-mentioned intermediate layer forming composition is preferably 50 ppm or more, more preferably 70 ppm or more, and even more preferably 90 ppm or more, based on the total mass of the intermediate layer forming composition in terms of metal. The upper limit of the alkali metal salt content in the above-mentioned intermediate layer forming composition is preferably 300 ppm or less, more preferably 250 ppm or less, and even more preferably 200 ppm or less, based on the total mass of the intermediate layer forming composition in terms of metal. Furthermore, the range of alkali metal salt content in the above-mentioned intermediate layer forming composition is preferably 50 to 500 ppm, more preferably 50 to 300 ppm, even more preferably 70 to 250 ppm, and even more preferably 90 to 200 ppm, based on the total mass of the intermediate layer forming composition in terms of metal. If the alkali metal salt content in the above-mentioned intermediate layer forming composition is 50 ppm or more in terms of metal relative to the total mass of the intermediate layer forming composition, adhesion defects will not occur during co-extrusion molding of the intermediate layer forming composition. Furthermore, if the alkali metal salt content in the above-mentioned intermediate layer forming composition is 500 ppm or less in terms of metal relative to the total mass of the intermediate layer forming composition, discoloration due to decomposition of the alkali metal salt is less likely to occur when molding the intermediate layer at high temperatures.

[0047] From the viewpoint of enabling stable melt molding over a long period of time, the above-mentioned intermediate layer forming composition preferably contains an alkaline earth metal salt. Examples of alkaline earth metals that constitute the above-mentioned alkaline earth metal salts include beryllium, magnesium, calcium, strontium, and barium, with magnesium, calcium, or barium being preferred.

[0048] Examples of the above-mentioned alkaline earth metal salts include carboxylates, phosphates, and borates, but acetates are preferred.

[0049] The lower limit of the content of the alkaline earth metal salt in the above-mentioned intermediate layer forming composition is preferably 10 ppm or more, more preferably 15 ppm or more, and even more preferably 20 ppm or more, based on the total mass of the intermediate layer forming composition in terms of metal. The upper limit of the content of the alkaline earth metal salt in the above-mentioned intermediate layer forming composition is preferably 50 ppm or less, more preferably 45 ppm or less, and even more preferably 40 ppm or less, based on the total mass of the intermediate layer forming composition in terms of metal. Furthermore, the range of the content of the alkaline earth metal salt in the above-mentioned intermediate layer forming composition is preferably 10 to 50 ppm, more preferably 15 to 45 ppm, and even more preferably 20 to 40 ppm, based on the total mass of the intermediate layer forming composition in terms of metal. If the content of the alkaline earth metal salt in the above-mentioned intermediate layer forming composition is 10 ppm or more in terms of metal relative to the total mass of the intermediate layer forming composition, fish eyes are less likely to occur during long-term melt extrusion at high temperatures. Furthermore, if the content of the alkaline earth metal salt in the above-mentioned intermediate layer forming composition is 50 ppm or less in terms of metal relative to the total mass of the intermediate layer forming composition, foaming is less likely to occur in the extruder die during melt molding at high temperatures (around 280°C), and voids and holes are less likely to occur. Moreover, if the content of the alkaline earth metal salt in the above-mentioned intermediate layer forming composition is within the range of 10 to 50 ppm in terms of metal relative to the total mass of the intermediate layer forming composition, the viscosity of the intermediate layer forming composition does not change significantly even in a molten state at high temperatures for a long period of time, allowing for long-term operation and resulting in molded products with a good appearance.

[0050] The above-mentioned intermediate layer forming composition preferably contains a phosphoric acid derivative, from the viewpoint of reducing discoloration during melt molding and making it less prone to gelation. Examples of the above-mentioned phosphoric acid derivatives include phosphoric acid (H3PO4) and phosphates. The above-mentioned phosphate may be included in any of the forms of primary, secondary, and tertiary phosphates, and the cation species is not particularly limited, but at least one selected from the group consisting of alkali metal phosphates and alkaline earth metal phosphates is preferred. Examples of the above-mentioned phosphates include sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate, with potassium dihydrogen phosphate being preferred.

[0051] The lower limit of the content of the phosphoric acid derivative in the above intermediate layer forming composition is preferably 10 ppm or more, and more preferably 20 ppm or more, in terms of phosphoric acid (H3PO4) relative to the total mass of the intermediate layer forming composition. The upper limit of the content of the phosphoric acid derivative in the above intermediate layer forming composition is preferably 100 ppm or less, more preferably 80 ppm or less, and even more preferably 60 ppm or less, in terms of phosphoric acid (H3PO4) relative to the total mass of the intermediate layer forming composition. Furthermore, the range of the content of the phosphoric acid derivative in the above intermediate layer forming composition is preferably 10 to 100 ppm, more preferably 10 to 80 ppm, and even more preferably 20 to 60 ppm, in terms of phosphoric acid (H3PO4) relative to the total mass of the intermediate layer forming composition. If the content of the phosphoric acid derivative in the above intermediate layer forming composition is 10 ppm or more in terms of phosphoric acid (H3PO4) relative to the total mass of the intermediate layer forming composition, the effect of preventing discoloration during melt molding of the intermediate layer is further enhanced, and the risk of appearance defects due to discoloration of the intermediate layer is eliminated. If the content of the phosphoric acid derivative in the above intermediate layer forming composition is 100 ppm or less in terms of phosphoric acid (H3PO4) relative to the total mass of the intermediate layer forming composition, gelation is suppressed during melt molding of the intermediate layer, especially during melt molding at high temperatures, and the risk of appearance defects due to fish eyes and excessive gel formation is eliminated.

[0052] In the above-mentioned intermediate layer forming composition, an embodiment is useful and preferred in which the boron compound is contained in an amount of 100 to 5000 ppm in terms of boric acid (H3BO3), at least one selected from the group consisting of carboxylic acids and / or salts thereof in an amount of 100 to 1000 ppm in terms of carboxylic acid, and the alkali metal salt in an amount of 50 to 300 ppm in terms of metal, relative to the total mass of the intermediate layer forming composition.

[0053] Furthermore, in the above-mentioned intermediate layer forming composition, an embodiment containing 10 to 50 ppm of the alkaline earth metal salt in terms of metal content relative to the total mass of the intermediate layer forming composition is equally useful and equally preferred. Furthermore, in the above-mentioned intermediate layer forming composition, an embodiment in which the boron compound is included in addition to the alkaline earth metal salt at a concentration of 100 to 5000 ppm in terms of boric acid (H3BO3) relative to the total mass of the intermediate layer forming composition is more useful and more preferable.

[0054] The method for mixing the EVOH copolymer with the various compounds described above in preparing the above-mentioned intermediate layer forming composition is not particularly limited. For example, methods include immersing the EVOH copolymer in a solution containing the various compounds, melting the EVOH copolymer and mixing it with the various compounds, and dissolving the EVOH copolymer in a suitable solvent and mixing it with the various compounds. When immersing the EVOH copolymer in a solution containing the various compounds, the concentration of the various compounds in the solution is not particularly limited. Furthermore, the solvent of the solution containing the various compounds is not particularly limited, but water is preferred for handling reasons. When the EVOH copolymer is obtained by saponifying an ethylene-vinyl acetate copolymer, the mass of the solution used when immersing the saponified ethylene-vinyl acetate copolymer (hereinafter also simply referred to as "saponified product") in a solution containing the various compounds is preferably 3 times or more, and more preferably 20 times or more, the dry mass of the saponified product. The immersion time when immersing the above EVOH copolymer in a solution containing the above various compounds varies depending on the form of the EVOH copolymer. However, if the EVOH copolymer is a roughly cubic chip with sides of about 1 to 10 mm, 1 hour or more is preferable, and 2 hours or more is more preferable.

[0055] The lower limit of the decomposition initiation temperature (JIS K 7120:1987) for the above-mentioned intermediate layer-forming composition is preferably 350°C or higher, more preferably 355°C or higher, and even more preferably 360°C or higher. Furthermore, the upper limit of the decomposition initiation temperature for the above-mentioned intermediate layer-forming composition is preferably 400°C or lower. Moreover, the range of the decomposition initiation temperature for the above-mentioned intermediate layer-forming composition is preferably 350 to 400°C, more preferably 355 to 400°C, and even more preferably 360 to 400°C. If the decomposition initiation temperature of the above-mentioned intermediate layer forming composition is within the above range, molding defects due to resin degradation are less likely to occur even during long-term operation at high temperatures.

[0056] The above EVOH copolymer may be used individually, or two or more EVOH copolymers with different degrees of polymerization, ethylene content, and saponification may be blended and used together. Furthermore, other thermoplastic resins other than EVOH copolymers may be blended into the above-mentioned intermediate layer forming composition, within a range that does not impede the effects of the present invention. Examples of the above-mentioned other thermoplastic resins include polyolefins such as polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene propylene copolymer, copolymer of ethylene and α-olefins having 4 or more carbon atoms, copolymer of polyolefin and maleic anhydride, ethylene-vinyl ester copolymer, ethylene-acrylic acid ester copolymer, and modified polyolefins obtained by grafting these polyolefins with unsaturated carboxylic acids or their derivatives; polyamides such as nylon 6, nylon 66, and nylon 6 / 66 copolymer; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyurethane; polyacetal; and vinyl polymers such as polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylonitrile, and modified polyvinyl alcohol.

[0057] Furthermore, the above-mentioned intermediate layer-forming composition may also contain additives other than the various compounds described above. Examples of such additives include plasticizers, stabilizers, surfactants, colorants, ultraviolet absorbers, antistatic agents, desiccants, crosslinking agents, metal salts, fillers, and reinforcing agents. The reinforcing agents include, for example, various fibers. The content of the above-mentioned additives in the above-mentioned intermediate layer-forming composition is not particularly limited as long as it does not hinder the effects of the present invention. Furthermore, while the molding method for the above-mentioned intermediate layer forming composition is not particularly limited, a method of co-extruding the inner layer, the intermediate layer, and the outer layer described later is preferred.

[0058] The content of the EVOH copolymer in the intermediate layer is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass, based on the total mass of the intermediate layer.

[0059] <Outer layer> The outer layer is a layer containing a polyolefin having units based on acid anhydrides, or a layer in which a layer containing a polyolefin having units based on acid anhydrides and a layer containing a polyolefin not having units based on acid anhydrides are directly laminated.

[0060] Examples of polyolefins that do not have units based on the above-mentioned acid anhydrides include poly-α-olefins (hereinafter also referred to as "PAO") obtained by polymerizing α-olefins. The above-mentioned α-olefins are alkenes in which the carbon-carbon double bond is at the α position, i.e., terminal. α-olefins with four or more carbon atoms, such as 1-butene, 1-pentene, and 1-hexene, are used as comonomers when copolymerizing, forming short branched structures within the molecule.

[0061] Many PAOs have flexible alkyl groups as branched structures. Because these alkyl groups can adopt various conformations, it is difficult to align the polymer chains in an ordered manner. Therefore, PAOs with these alkyl groups as branched structures do not easily crystallize or solidify, and remain as viscous liquids even at low temperatures.

[0062] Polyethylene copolymerized with α-olefins having 5 or more carbon atoms, such as 1-hexene, 1-heptene, or 1-octene, is more flexible than ethylene homopolymers without branched structures and copolymers of relatively simple linear ethylene with α-olefins having 5 or fewer carbon atoms. Although methyl groups are included as branched structures in propylene-based units and ethyl groups in 1-butene-based units, these alkyl groups are short, so the flexibility of copolymers of ethylene with propylene or 1-butene is not significantly different from that of polyethylene homopolymers. Similarly, the flexibility of propylene or 1-butene homopolymers is not significantly different from that of ethylene homopolymers.

[0063] Examples of polyolefins that do not have units based on the above acid anhydride include homopolymers of ethylene and copolymers of ethylene with at least one selected from the group consisting of α-olefins other than ethylene and unsaturated group-containing polar compounds other than compounds having acid anhydride groups. These polymers are collectively referred to as "ethylene-based polyolefins." The content of ethylene-based units (E units) in the above ethylene-based polyolefins is preferably 80 mol% or more, and more preferably 90 mol% or more, based on the total number of moles of units constituting the above ethylene-based polyolefins. Examples of the above ethylene-based polyolefins include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ethylene-vinyl acetate copolymer, ethylene-ethyl acrylic acid ester copolymer, and ethylene-based ionomers.

[0064] The density of the above ethylene-based polyolefins is 0.86 to 0.98 g / cm³. 3 Preferably, 0.90-0.94 g / cm³ 3 This is preferable. The density of the above ethylene-based polyolefins was measured in accordance with JIS K 7112:1999. The MFR (190°C) of the above ethylene-based polyolefin is preferably 0.05 to 100 g / 10 min, and more preferably 0.5 to 50 g / 10 min. The MFR of the above ethylene-based polyolefins was measured in accordance with ASTM D1238 at a temperature of 190°C and under a load of 2.16 kgf. The Vicat softening point of the above ethylene-based polyolefin is preferably 70 to 120°C, and more preferably 75 to 110°C. The Vicat softening point of the above ethylene-based polyolefins was measured in accordance with JIS K 7206:2016.

[0065] Furthermore, polyolefins that do not have units based on the above acid anhydride include, for example, homopolymers of propylene and copolymers of propylene with at least one selected from the group consisting of α-olefins other than propylene and unsaturated group-containing polar compounds other than compounds having acid anhydride groups. These polymers are collectively referred to as "propylene-based polyolefins." The content of propylene-based units (P units) in the above propylene-based polyolefins is preferably 70 mol% or more, and more preferably 80 mol% or more, based on the total number of moles of units constituting the above propylene-based polyolefin. Polypropylene is preferred as the above propylene-based polyolefin.

[0066] The density of the above propylene-based polyolefin is 0.83 g / cm³. 3 The above is preferable, with a range of 0.89 to 0.92 g / cm³. 3 This is preferable. The melting point of the above propylene-based polyolefin is preferably 120 to 170°C, and more preferably 130 to 165°C. The melting points of the above propylene-based polyolefins were measured using DSC at a heating rate of 10°C / min, in accordance with JIS K 7121:1987. The MFR (190°C) of the above propylene-based polyolefin is preferably 0.01 to 100 g / 10 min, and more preferably 0.05 to 50 g / 10 min. The Vicat softening point of the above propylene-based polyolefin is preferably 100 to 160°C, and more preferably 110 to 160°C. The density, MFR, and Vicat softening point of the above-mentioned propylene-based polyolefin are measured in the same manner as the density, MFR, and Vicat softening point of the above-mentioned ethylene-based polyolefin.

[0067] Examples of polyolefins having units based on the above-mentioned acid anhydride include polymers of α-olefins and compounds having acid anhydride groups, polymers obtained using a chain transfer agent or polymerization initiator that introduces acid anhydride groups during the polymerization of α-olefins, and polyolefins that do not have units based on the above-mentioned acid anhydride, to which acid anhydrides such as maleic anhydride have been grafted. A method for grafting acid anhydrides onto polyolefins that do not have units based on the above-mentioned acid anhydride includes, for example, grafting acid anhydrides such as maleic anhydride onto polyolefins that do not have units based on the above-mentioned acid anhydride during a post-processing step such as pelletizing or compounding. Specifically, a method can be used in which a peroxide is reacted with the polyolefins that do not have units based on the above-mentioned acid anhydride to extract hydrogen atoms, and an acid anhydride having an unsaturated bond is grafted onto the radical generation site (unsaturated bond).

[0068] The layer containing the polyolefin having units based on the above-mentioned acid anhydride may also contain other components in addition to the polyolefin having units based on the above-mentioned acid anhydride. Other components mentioned above include, for example, thermoplastic resins other than polyolefins having units based on the above-mentioned acid anhydride. Examples of such thermoplastic resins include thermoplastic polyimide, polyarylate, and polysulfone. Other components mentioned above may include additives such as heat stabilizers, fillers, pigments, or UV absorbers.

[0069] The layer containing the polyolefin that does not have units based on the above acid anhydride may also contain other components besides the polyolefin that does not have units based on the above acid anhydride. Other components mentioned above include, for example, thermoplastic resins other than polyolefins having units based on the above-mentioned acid anhydride. Examples of such thermoplastic resins include thermoplastic polyimide, polyarylate, and polysulfone. Other components mentioned above may include additives such as heat stabilizers, fillers, pigments, or UV absorbers.

[0070] The layer containing the polyolefin having the above-mentioned acid anhydride-based units is preferably formed by melt-extrusion molding of a first outer layer-forming composition containing a polyolefin that does not have the above-mentioned acid anhydride-based units. Furthermore, the layer containing a polyolefin that does not have units based on the above-mentioned acid anhydride is preferably formed by melt extrusion molding of a second outer layer forming composition containing a polyolefin that does not have units based on the above-mentioned acid anhydride. It is preferable to co-extrude the first outer layer forming composition and the second outer layer forming composition to form the layer containing a polyolefin having units based on the above acid anhydride and the layer containing a polyolefin not having units based on the above acid anhydride.

[0071] The content of the polyolefin having units based on the above acid anhydride in the outer layer is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass, based on the total mass of the outer layer.

[0072] <Fuel filler pipe> In the fuel filler pipe of the present invention, the thickness of the inner layer is preferably 0.1 to 0.8 mm, and more preferably 0.2 to 0.5 mm. Furthermore, in the fuel filler pipe of the present invention, the thickness of the intermediate layer is preferably 0.1 to 0.5 mm, and more preferably 0.2 to 0.5 mm. Furthermore, in the fuel filler pipe of the present invention, the thickness of the outer layer is preferably 0.8 to 5 mm, and more preferably 1.0 to 3.0 mm. In the fuel filler pipe of the present invention, the sum of the thicknesses of the inner layer, intermediate layer, and outer layer is preferably 1.0 to 20.0 mm. Furthermore, the thickness of the inner layer is preferably 10 to 30% of the thickness of the outer layer. Furthermore, the thickness of the intermediate layer is preferably 10 to 30% of the thickness of the outer layer.

[0073] In the fuel filler pipe of the present invention, it is preferable that ester bonds are present at both the first interface between the inner layer and the intermediate layer, and the second interface between the intermediate layer and the outer layer. The ester bond described above is preferably an ester bond formed from an acid anhydride group and a hydroxyl group. The presence of ester bonds at both the first and second interfaces results in good interlayer adhesion between the inner, intermediate, and outer layers. The presence of the ester bond was determined from the absorption peak of the carbonyl group of the ester bond detected by IR.

[0074] Furthermore, it is preferable that the peel strength of both the first interface between the inner layer and the intermediate layer, and the second interface between the intermediate layer and the outer layer, be 30 N / cm or more, and more preferably 40 N / cm or more. The above peel strength test was performed by cutting a laminated pipe into 20cm lengths, and then cutting each lengthwise to create a test specimen. The outer and inner layers were forcibly separated 1cm from the end, and a 180° adhesion test was performed using a Tensilon universal testing machine with the outer and inner layers sandwiched between the pipes at a tensile speed of 50mm / min. The maximum strength was read from the maximum point of the SS curve and defined as the interlaminar peel strength (N / cm).

[0075] Furthermore, in the fuel filler pipe of the present invention, it is also preferable that neither the first interface between the inner layer and the intermediate layer, nor the second interface between the intermediate layer and the outer layer, has any other layer such as an adhesive layer. In embodiments that include other layers such as adhesives, components contained in these other layers may be discharged into the fuel, potentially leading to serious problems such as clogging of the filter before the engine (cutting off the fuel supply to the engine), clogging of the activated carbon in the fuel-cutting canister (cutting off the fuel vapor from the vehicle), and malfunction of valves in various transportation lines.

[0076] The fuel filler pipe of the present invention has a fuel permeability coefficient of 6.0 g·mm / (m³) for the inner layer, which was determined by the cup method below using a test fuel (hereinafter also referred to as "CE10") of isooctane:toluene:ethanol (volume ratio) = 45:45:10 at 60°C. 2 It is preferable that the time is 24 hours or less. (Cup method) A test specimen with a thickness of 100 μm is prepared. Following the cup method specified in JIS Z 0208:1976, 4.6 g of the designated test fuel is applied to a permeation area of ​​11.33 cm². 2 The sample is placed in a cup, the top of the cup is covered with a test piece, and the mass loss after holding it at 60°C for 10 days is recorded. The fuel permeability coefficient of the polymer is then determined from the following formula. Fuel permeability coefficient = Mass loss (g) × Thickness of test specimen (mm) / Permeability area (m²) 2 ) x Transmission days) The fuel permeability coefficient can be reduced by increasing the fluorine content or crystallinity of the ETFE copolymer in the inner layer.

[0077] Furthermore, the fuel filler pipe of the present invention contains CE10, and the surface resistivity of the inner layer after exposure to a temperature of 40°C for 1000 hours is 10 5 A density of Ω / sq. or less is preferable. Since polymers such as ETFE copolymers generally have high surface resistivity, adding conductive fillers as described above can lower their surface resistivity.

[0078] The inner layer of the fuel filler pipe of the present invention preferably has a tensile breaking strength of 55% or more, and more preferably 75% or more, relative to the initial tensile breaking strength after exposure to an ambient temperature of 200°C for 1000 hours. Furthermore, the inner layer of the fuel filler pipe of the present invention preferably has a tensile breaking elongation of 65% or more, and more preferably 75% or more, relative to the initial tensile breaking elongation after exposure to an ambient temperature of 200°C for 1000 hours.

[0079] The inner layer of the fuel filler pipe of the present invention preferably has a tensile breaking strength of 70% or more remaining relative to the initial tensile breaking strength after exposure to an ambient temperature of 220°C for 1000 hours. It is also preferable that the tensile breaking elongation after exposure to an ambient temperature of 220°C for 1000 hours remains at 65% or more relative to the initial tensile breaking elongation.

[0080] Exposure to high temperatures such as 200°C or 220°C can cause thermal oxidative degradation. To prevent this thermal oxidative degradation, for example, in the case of ETFE copolymers, one can increase the number of CF bonds with high bond energy, specifically by increasing the number of TFE units or stabilizing the unstable groups at the ends. Another way to prevent this thermal oxidative degradation is to use a chain transfer agent that stabilizes the ends during polymerization.

[0081] The present invention provides a method for manufacturing fuel filler pipes, which includes a method of melt extrusion using an extruder corresponding to the number of layers or the number of materials, a method of simultaneous lamination inside or outside the die (co-extrusion method), and a method of first manufacturing single-layer pipes or laminated pipes manufactured by the above method, and then sequentially laminating resin onto the outside, using an adhesive as necessary (coating method).

[0082] Furthermore, if the resulting laminated pipe has a complex shape, or if the molded product is to be formed by heat bending after molding, it is also possible to remove residual strain from the molded product by heat-treating the laminated pipe for 0.01 to 10 hours at a temperature below the lowest melting point of the resins constituting the laminated pipe, after forming the laminated pipe, in order to obtain the desired molded product.

[0083] The laminated pipe described above may have a corrugated region. The corrugated region is a region formed in a corrugated shape, bellows shape, accordion shape, or corrugated shape, etc. The corrugated region is not limited to being formed along the entire length of the laminated pipe, but may be partially formed in an appropriate region along the middle. The corrugated region can be easily formed, for example, by first forming a straight pipe, and then subsequently molding it to a predetermined corrugated shape. The laminated pipe has shock absorption properties and is easy to install due to having the corrugated region. Furthermore, it is possible to add necessary parts such as connectors, or to bend it into an L-shape, U-shape, etc.

[0084] A solid or sponge-like protective member (protector) made of epichlorohydrin rubber (ECO), acrylonitrile / butadiene rubber (NBR), a mixture of NBR and polyvinyl chloride, chlorosulfonated polyethylene rubber, chlorinated polyethylene rubber, acrylic rubber (ACM), chloroprene rubber (CR), ethylene / propylene rubber (EPR), ethylene / propylene / diene rubber (EPDM), a mixture of NBR and EPDM rubber, or a thermoplastic elastomer such as vinyl chloride, olefin, ester, or amide may be placed on all or part of the outer circumference of the laminated pipe formed in this manner, taking into consideration protection from stone chips, abrasion from other parts, or flame resistance.

[0085] The protective member described above may be made into a sponge-like porous material by known methods. By making the protective member a porous material, a lightweight protective part with excellent heat insulation properties can be formed. Furthermore, the material cost of the fuel filler pipe of the present invention can also be reduced. The strength of the protective member may be improved by adding reinforcing materials such as glass fibers. The shape of the protective member described above is not particularly limited, but it is usually a cylindrical member or a block-shaped member having a recess for receiving laminated pipes. When the protective member is a cylindrical member, it can be manufactured by inserting laminated pipes into a pre-fabricated cylindrical member, or by extruding a cylindrical member onto laminated pipes to create a tight bond between the two. To bond the protective member and the laminated pipes together, adhesive is applied to the inner surface or recess of the protective member as needed, the laminated pipes are inserted or fitted into it, and the two are tightly bonded to form an integrated structure of the laminated pipes and the protective member. Furthermore, this integrated structure can be further reinforced with metal or the like.

[0086] The outer diameter of the laminated pipe described above is designed to take into account the flow rate of fuel such as gasoline, and the wall thickness is designed to be such that the permeability of the fuel does not increase, the burst pressure of a normal pipe is maintained, and the pipe maintains a degree of flexibility that is easy to assemble and has good vibration resistance during use, but it is not limited to these dimensions. The outer diameter of the laminated pipe described above is preferably 4 to 30 mm, the inner diameter is preferably 3 to 25 mm, and the wall thickness is preferably 0.5 to 5 mm. [Examples]

[0087] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following description.

[0088] [Evaluation Method] <mfr> Unless otherwise specified, MFR was measured in accordance with ASTM D3159 under conditions of 297°C and 49N load.

[0089] <Melting point (°C)> The endothermic peak was determined using a scanning differential thermal analyzer (SII Corporation, DSC7200) when the sample was heated to 300°C at a rate of 10°C / min in an air atmosphere.

[0090] <Content of acid anhydride groups (mol%)> Using a 200 μm thick film obtained by press-molding a fluorine-containing copolymer, a Fourier transform infrared spectrometer (Thermo Fisher Scientific, Nicolet iS10) was used to measure 1800-1900 cm². -1 The intensity of absorption derived from acid anhydride residues appearing in the sample was measured, and the acid anhydride residue content was calculated.

[0091] <Composition (mol%) of fluorine-containing copolymer> The total fluorine content was calculated from the results of total fluorine content measurement and molten F-NMR measurement.

[0092] <Delamination strength> A laminated pipe was cut into 20 cm lengths, and then cut lengthwise to create test specimens. The outer and inner layers were forcibly separated 1 cm from the end, and a 180° adhesion test was performed using a Tensilon universal testing machine with the outer and inner layers sandwiched between the pipes at a tensile speed of 50 mm / min. The maximum strength was read from the maximum point of the SS curve and defined as the interlaminar peel strength (N / cm).

[0093] <Fuel permeability coefficient> The fuel permeability coefficient of the fluorine-containing copolymer was measured in accordance with the cup method specified in JIS Z0208. Specifically, 9.5 to 10 g of fuel (CE10) (isooctane:toluene:ethanol = 45:45:10 volume ratio) was permeated over a permeation area of ​​28.26 cm². 2 The fuel was placed in a cup, the top of the cup was covered with a 100 μm thick ETFE copolymer (A) film obtained by press molding, and the fuel permeability coefficient was determined from the mass loss after being held at 60°C for 10 days. A lower fuel permeability coefficient indicates superior fuel barrier properties.

[0094] <Conductive> The conductivity of the laminated pipes was measured in accordance with SAE J-2260.

[0095] <Heat aging resistance: Remaining tensile strength, remaining tensile elongation> The residual strength for heat aging is the ratio of the tensile breaking strength after exposure to an ambient temperature of 200°C or 220°C for 500 hours or 1000 hours to the initial tensile breaking strength, and the residual elongation for heat aging is the ratio of the tensile breaking elongation after exposure to an ambient temperature of 200°C or 220°C for 500 hours or 1000 hours to the initial tensile breaking elongation. • Measurement method: A tensile test in accordance with ASTM D638 is used to express the aging rate relative to the initial value, based on the strength and elongation at fracture. • Test specimen: Type-V shaped dumbbell as described in ASTMD 638, tensile speed: 50 mm / min

[0096] (Materials used) 1. (D) Polyethylene for the outermost layer D-1: Made of Prime Polymer (high-density polyethylene) Grade name: Hizex 5600B, Density: 0.935 (g / cm³) 3 ) MFR:0.45(g / 10min): Measurement temperature 190℃ Grade name: Hizex 6700B, Density: 0.958 (g / cm³) 3 ) MFR:0.4(g / 10min) at 190℃*2.16kgf • Manufactured by Nippon Polyethylene Co., Ltd. Grade name: Novatec HD HB420R, Density = 0.956 g / cm³ 3 , MFR=0.2(g / 10min) at 190℃*2.16kgf

[0097] 2. (C) For outer layer: Acid anhydride modified polyethylene C-1: Manufactured by Nippon Polyethylene Co., Ltd. (Maleic anhydride graft copolymer high-density polyethylene) Grade Name: Adtex DU1022N Tm: 128℃ MFR: 25 (190℃ * 2.16kgf)

[0098] 3.(B) For middle layer: EVOH B-1: Kuraray EVAL LA170B, Ethylene content 27 mol%, Saponification degree: 99% or higher, Tm: 191℃, MFR: 2.1 (210℃ * 2.16 kgf)

[0099] 4. (A) For inner layer: Conductive ETFE composition with added ETFE copolymer and conductive filler. Examples 1 and 2 used a conductive ETFE composition (A-2) made from an ETFE copolymer (A-1) as the inner layer. Example 3 used a conductive ETFE composition (A-4) made of an ETFE copolymer (A-3) as the inner layer. Example 4 used a conductive ETFE composition (A-6) made of an ETFE copolymer (A-5) as the inner layer. Example 5 used an ETFE copolymer (A-1) as the inner layer. Comparative Example 1 used a conductive composition (A-8) with a polymer (A-7) that is not an ETFE-based copolymer of the present invention as the inner layer.

[0100] Production of ETFE-based copolymer (A-1) A polymerization tank with a stirring blade and an internal volume of 94 L was degassed, and 71.3 kg of 1-hydrotridecafluorohexane, 20.4 kg of 1,3-dichloro-1,1,2,2,3-pentafluoropropane (AGC AK225cb, hereafter referred to as AK225cb) as a chain transfer agent, 562 g of CH2=CH(CF2)2F, and 4.45 g of itaconic anhydride (IAN) were charged in. The temperature inside the polymerization tank was raised to 66°C, and the pressure was increased to 1.5 MPa / G with TFE / E (molar ratio: 89 / 11) gas. 1 L of a 0.7% hydrotridecafluorohexane solution of tert-butylperoxypivalate was charged in as a polymerization initiator to start the polymerization. A monomer mixture gas of TFE / E (molar ratio: 59.5 / 40.5) was continuously added to maintain a constant pressure during polymerization. In addition, an amount of CH2=CH(CF2)2F equivalent to 3.3 mol% of the total moles of TFE and E added during polymerization, and an amount of IAN equivalent to 0.8 mol%, were continuously added in a 1% solution of AK225cb. 9.9 hours after the start of polymerization, when 7.28 kg of the monomer mixture gas had been added, the temperature inside the polymerization vessel was lowered to room temperature and purged to atmospheric pressure. The obtained slurry-like fluorine-containing copolymer was placed in a 200 L granulation tank containing 77 kg of water, and granulation was carried out while stirring and heating to 105°C, removing the solvent by distillation. The resulting granules were dried at 150°C for 15 hours to obtain 6.9 kg of fluorine-containing copolymer granules. The composition of the obtained fluorine-containing copolymer was 57.2 / 38.5 / 0.48 / 3.5 in molar ratios of polymerization units based on TFE / E / IAN / CH2=CH(CF2)2. The melting point was 230°C. This granulated material was melted using an extruder at 280°C with a residence time of 2 minutes to obtain pellets of a fluorine-containing copolymer. Hereinafter, this ETFE-based copolymer will be referred to as (A-1).

[0101] Manufacturing of conductive ETFE composition (A-2) 100 parts by mass of ETFE copolymer (A-1) and 17 parts by mass of carbon black (manufactured by Denki Kagaku Co., Ltd.) were premixed and supplied to a twin-screw molten mixer (manufactured by Toshiba Machine Co., Ltd., model: TEM-48SS). The mixture was melt-kneaded at a cylinder temperature of 240-300°C, and the molten resin was extruded into strands. These strands were then introduced into a water tank to cool them with water, cut with a pelletizer, and dried in a 120°C dryer for 10 hours to remove moisture, thereby obtaining pellets of conductive fluorine-containing copolymer. Hereinafter, this conductive ETFE composition will be referred to as (A-2).

[0102] Production of ETFE-based copolymer (A-3) Granulated fluorine-containing copolymers were obtained in the same manner as for ETFE-based copolymers (A-1). The composition of the obtained fluorine-containing copolymer was 57.2 / 38.5 / 0.43 / 3.3 in molar ratios of polymerization units based on TFE / E / IAN / CH2=CH(CF2)4F. The melting point was 225°C. Using this granule, ETFE copolymer pellets were obtained in the same manner as with ETFE copolymer (A-1). Hereafter, this ETFE copolymer will be referred to as (A-3).

[0103] Manufacturing of conductive ETFE composition (A-4) In the production of conductive ETFE composition (A-2), a pellet of conductive fluorine-containing copolymer was obtained by the same method, except that ETFE copolymer (A-1) was replaced with ETFE copolymer (A-3). Hereinafter, this conductive ETFE composition will be referred to as (A-4).

[0104] Production of ETFE-based copolymer (A-5) A stainless steel polymerization tank with an internal volume of 1.2 L (liters), equipped with a stirrer and jacket, was evacuated. Then, 1180 g of CF3CH2OCF2CF2H, 5.7 g of methanol, and 7.0 g of CH2=CH(CF2)2F were added. While stirring the inside of the polymerization tank, 177 g of TFE and 6.1 g of E were added, and then warm water was flowed through the jacket to raise the temperature inside the polymerization tank to 66°C. At this time, the pressure inside the polymerization tank was 1.54 MPaG. After the internal temperature stabilized, 9 mL of a 2 mass% CF3CH2OCF2CF2H solution of tert-butylperoxypivalate was injected under pressure to start polymerization. During polymerization, a mixed gas with a TFE / E ratio of 60 / 40 molar ratio was added to maintain a constant internal pressure of 1.54 MPaG. In addition, 0.6 mL of CH2=CH(CF2)2F was added for every 10 g of TFE / E mixed gas consumed during polymerization, and 2 mL of a 1.8 mass% CF3CH2OCF2CF2H solution of itaconic anhydride was added for every 5 g of TFE / E mixed gas consumed. The saturated solubility of itaconic anhydride in CF3CH2OCF2CF2H at 25°C was 5 mass%. 240 minutes after the start of the reaction, 100 g of a TFE / E = 60 / 40 molar mixed gas was added, at which point the polymerization vessel was cooled and the polymerization was terminated. Subsequently, the residual monomer gas was purged from the polymerization tank to atmospheric pressure, the slurry was transferred to a 2L container, an equal volume of water was added to the slurry, and the polymerization medium, chain transfer agent, residual monomer, and polymer were separated while heating (30-90°C). The obtained polymer was dried in an oven at 150°C to obtain a white powder. The composition of this polymer was TFE / E / CH2=CH(CF2)2F / Itaconic anhydride = 54.8 / 42.6 / 2.2 / 0.4 mol%, and its melting point was 239°C. Using this granule, a fluorine-containing copolymer pellet was obtained in the same manner as with the ETFE copolymer (A-1). Hereafter, this ETFE copolymer will be referred to as (A-5).

[0105] Manufacturing of conductive ETFE-based composition (A-6) In the production of conductive ETFE composition (A-2), a pellet of conductive fluorine-containing copolymer was obtained by the same method, except that ETFE copolymer (A-1) was replaced with ETFE copolymer (A-5). Hereinafter, this conductive ETFE composition will be referred to as (A-6).

[0106] Production of polymer (A-7) Granulated fluorine-containing copolymers were obtained in the same manner as for ETFE copolymer (A-1), except that the amount of CH2=CH(CF2)2F equivalent to 3.3 mol% of the total number of moles of TFE and E charged during polymerization was changed to an amount equivalent to 0.8 mol%, and the amount of IAN equivalent to 0.8 mol% was changed to an amount equivalent to 0.5 mol%. The composition of the obtained fluorine-containing copolymer was 58.6 / 40.1 / 0.3 / 0.6 in molar ratios of polymerization units based on TFE / E / IAN / CH2=CH(CF2)4F. The melting point was 255°C. Using this granule, ETFE copolymer pellets were obtained in the same manner as with ETFE copolymer (A-1). Hereinafter, this polymer will be referred to as (A-7).

[0107] Manufacturing of conductive composition (A-8) (A-7) 100 parts by mass of ETFE copolymer and 17 parts by mass of carbon black (manufactured by Denki Kagaku Co., Ltd.) were premixed and supplied to a twin-screw fusion kneader (manufactured by Toshiba Machine Co., Ltd., model: TEM-48SS). The mixture was melt-kneaded at a cylinder temperature of 260-320°C, and the molten resin was extruded into strands. These strands were then introduced into a water tank to cool them with water, cut with a pelletizer, and dried in a 120°C dryer for 10 hours to remove moisture, thereby obtaining pellets of conductive fluorine-containing copolymer. Hereinafter, this conductive composition will be referred to as (A-8).

[0108] [Example 1] Using the above-mentioned (A) conductive ETFE composition (A-2), (B) EVOH (B-1), (C) acid anhydride-modified polyethylene (C-1), and (D) high-density polyethylene (D-1), a corrugator machine manufactured by Mirai Seikou Co., Ltd. was attached to the outlet of a 4-layer pipe molding machine manufactured by Plastics Engineering Laboratory Co., Ltd., and a bellows-shaped 4-layer pipe including a straight section was formed. (A) was melted separately at an extrusion temperature of 300°C, (B) at an extrusion temperature of 240°C, (C) at an extrusion temperature of 230°C, and (D) at an extrusion temperature of 240°C. The extruded molten resins were then laminated using a co-extrusion pipe die, and the resulting molten material was then processed using a corrugator machine consisting of a bellows-shaped mold to obtain a laminated pipe with an inner diameter of 29 mm and an outer diameter of 35 mm, where the layer configuration was (a) / (b) / (c) / (d) = 0.2 / 0.3 / 0.2 / 2.2 mm, with (A) being an ETFE copolymer (inner layer), (B) being an EVOH (b) layer, (C) being an acid anhydride modified polyethylene (c) layer, and (D) being a high-density polyethylene layer. Table 1 shows the results of the physical property measurements of the obtained laminated pipes.

[0109] [Example 2] Using the conductive ETFE composition (A-2), EVOH (B-1), and acid anhydride-modified polyethylene (C-1) described above, a corrugator machine manufactured by Mirai Seikou Co., Ltd. was attached to the outlet of a three-layer pipe molding machine manufactured by Plastics Engineering Laboratory Co., Ltd., and a bellows-shaped four-layer structure including a straight section was formed. (A) was melted separately at an extrusion temperature of 300°C, (B) at an extrusion temperature of 240°C, and (C) at an extrusion temperature of 230°C. The extruded molten resins were then laminated using a co-extrusion pipe die, and the resulting molten material was then processed using a corrugator machine consisting of a bellows-shaped mold to obtain a laminated pipe with an inner diameter of 29 mm and an outer diameter of 35 mm, where the layer structure consisted of (A) an ETFE copolymer (a) layer (inner layer), (B) an EVOH (b) layer, and (C) an acid anhydride modified polyethylene (c) layer, with a layer configuration of (a) / (b) / (c) = 0.2 / 0.3 / 2.5 mm. Table 1 shows the results of the physical property measurements of the obtained laminated pipes.

[0110] [Example 3] In Example 2, a laminated pipe with the layer configuration shown in Table 1 was obtained using the same method as in Example 1, except that (A) conductive ETFE composition (A-2) was changed to (A-4). Table 1 shows the results of the physical property measurements of the obtained laminated pipes.

[0111] [Example 4] In Example 2, a laminated pipe with the layer configuration shown in Table 1 was obtained in the same manner as in Example 1, except that (A) conductive ETFE composition (A-2) was changed to (A-6). Table 1 shows the results of the physical property measurements of the obtained laminated pipes.

[0112] [Example 5] In Example 2, instead of a corrugator machine, a cooling tank with sizing for straight pipes without a bellows shape was used to form a three-layer laminated pipe. The layer configuration at that time consisted of (A) an inner layer made of ETFE copolymer, (B) a layer made of EVOH, and (C) a layer made of acid anhydride-modified polyethylene, with a layer ratio of (a) / (b) / (c) = 0.18 / 0.27 / 1.55 ​​mm, resulting in a laminated pipe with an inner diameter of 12 mm and an outer diameter of 16 mm. Table 1 shows the results of the physical property measurements of the obtained laminated pipes.

[0113] [Comparative Example 1] In Example 1, a laminated pipe with the layer configuration shown in Table 1 was obtained using the same method as in Example 1, except that (A) conductive ETFE composition (A-2) was changed to (A-8). Table 1 shows the results of the physical property measurements of the obtained laminated pipes.

[0114] [Table 1]

[0115] The results for the heat aging resistance and fuel permeability of the inner layer are shown in Table 2.

[0116] [Table 2] < / mfr>

Claims

1. A fluorine-containing copolymer having units based on tetrafluoroethylene and units based on ethylene, having a carbonyl group-containing group, a melting point of 250°C or less, wherein the carbonyl group-containing group is derived from a unit based on a monomer having a carbonyl group-containing group, the monomer having a carbonyl group-containing group is at least one functional monomer selected from the group consisting of itaconic anhydride, itaconic acid, citraconic anhydride, and citraconic acid, and in the fluorine-containing copolymer, the molar ratio of units based on tetrafluoroethylene to units based on ethylene is 20 / 80 to 80 / 20, and the inner layer contains the fluorine-containing copolymer. An intermediate layer containing a non-fluorinated copolymer having ethylene-based units and vinyl alcohol-based units, and It consists only of an outer layer containing polyolefin, The inner layer, the intermediate layer, and the outer layer are directly laminated in this order. A fuel filler pipe, wherein the outer layer is a layer containing a polyolefin having units based on acid anhydride, or a layer in which a layer containing a polyolefin having units based on acid anhydride and a layer containing a polyolefin not having units based on acid anhydride are directly laminated.

2. The fluorine-containing copolymer is contained in an amount of 80 to 100% by mass relative to the total mass of the inner layer. The non-fluorine copolymer is contained in an amount of 80 to 100% by mass relative to the total mass of the intermediate layer. The outer layer contains 80 to 100% by mass of the polyolefin, A fuel filler pipe according to claim 1.

3. The fuel filler pipe according to claim 1, wherein the inner layer includes a conductive filler.

4. The surface resistivity of the inner layer is 10 ５ A fuel filler pipe according to claim 3, wherein the value is less than or equal to Ω / sq.

5. The surface resistivity of the inner layer is 10 ５ A fuel filler pipe according to claim 1, wherein the value is less than or equal to Ω / sq.

6. The fuel filler pipe according to claim 1, wherein the intermediate layer contains 25 to 50 mol% of ethylene-based units relative to the total units constituting the non-fluorine copolymer.

7. The fuel filler pipe according to claim 1, wherein in the intermediate layer, the vinyl alcohol-based units constituting the non-fluorine copolymer are obtained by saponifying 99% or more of the vinyl acetate-based units.

8. The fuel filler pipe according to claim 1, wherein the sum of the thicknesses of the inner layer, the intermediate layer, and the outer layer is 1.0 to 20.0 mm.

9. The fuel filler pipe according to claim 8, wherein the thickness of the inner layer is 10 to 30% of the thickness of the outer layer.

10. The fuel filler pipe according to claim 9, wherein the thickness of the intermediate layer is 10 to 30% of the thickness of the outer layer.

11. The fuel filler pipe according to claim 1, wherein ester bonds are present at both the first interface between the inner layer and the intermediate layer, and the second interface between the intermediate layer and the outer layer.

12. The fuel filler pipe according to claim 11, wherein the ester bond is an ester bond formed from an acid anhydride group and a hydroxyl group.

13. The fuel filler pipe according to claim 1, wherein both the first interface between the inner layer and the intermediate layer, and the second interface between the intermediate layer and the outer layer, have a peel strength of 30 N / cm or more.

14. The fuel permeability coefficient of the inner layer was determined to be 6.0 g / mm / (m) using the cup method below with CE10 at 60°C, which is a test fuel of isooctane:toluene:ethanol (volume ratio) = 45:45:

10. ２ - A fuel filler pipe according to claim 1, wherein the operating time is 24 hours or less. (Cup method) A test specimen with a thickness of 100 μm is prepared. Following the cup method specified in JIS Z 0208-1976, 4.6 g of the designated test fuel is applied to a permeation area of ​​11.33 cm². ２ The sample is placed in a cup, the top of the cup is covered with a test piece, and the mass loss after holding it at 60°C for 10 days is recorded. The fuel permeability coefficient of the polymer is then determined from the following formula. Fuel permeability coefficient = Mass loss (g) × Thickness of test specimen (mm) / Permeation area (m²) ２ ) x Transmission days)

15. A test fuel, CE10, with a volume ratio of isooctane:toluene:ethanol = 45:45:10, was sealed inside, and after exposure at a temperature of 40°C for 1000 hours, the surface resistivity of the inner layer was 10 ５ A fuel filler pipe according to claim 1, wherein the value is less than or equal to Ω / sq.

16. The fuel filler pipe according to claim 1, wherein both the first interface between the inner layer and the intermediate layer, and the second interface between the intermediate layer and the outer layer, have a peel strength of 40 N / cm or more.

17. The fuel filler pipe according to claim 1, wherein the inner layer has a remaining tensile breaking strength of 75% or more relative to the initial tensile breaking strength after exposure to an ambient temperature of 200°C for 1000 hours.

18. The fuel filler pipe according to claim 1, wherein the inner layer has a remaining tensile elongation of 75% or more relative to the initial tensile elongation after exposure to an ambient temperature of 200°C for 1000 hours.

19. The fuel filler pipe according to claim 1, wherein the inner layer has a remaining tensile breaking strength of 70% or more of the initial tensile breaking strength after exposure to an ambient temperature of 220°C for 1000 hours.

20. The fuel filler pipe according to claim 1, wherein the inner layer has a remaining tensile elongation of 65% or more relative to the initial tensile elongation after exposure to an ambient temperature of 220°C for 1000 hours.

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