JP7602882B2 - Fuel tube and manufacturing method thereof - Google Patents

Description

The present invention relates to fuels for automobiles, etc. (gasoline, alcohol-blended gasoline, diesel fuel, etc.)
The present invention relates to a fuel tube used for transporting fuel, etc., and a method for manufacturing the same.

In recent years, regulations on fuel gas evaporation surrounding automobiles have become stricter, and various types of low-permeability fuel tubes have been considered to meet these regulations. Conventionally, such fuel tubes have been made of fluororesin, but when stricter low fuel permeability performance is required, the thickness of the fluororesin layer must be increased, which has the drawback of making the hose expensive. Therefore, as resins that are cheaper than fluororesin and have excellent low fuel permeability, for example, polyphenylene sulfide resin (PPS), aromatic polyamide resins such as polyamide 9T (PA9T), and aromatic polyester resins such as polybutylene terephthalate (PBT) have been attracting attention. Various types of tubes equipped with low fuel permeability layers made of these resins have been proposed in recent years (for example, see Patent Documents 1 to 4).

Japanese Patent Application Publication No. 10-138372 JP 2003-287165 A JP 2003-110736 A JP 2011-214592 A

However, aromatic polyamide resins such as PA9T, which are used as tube materials and have particularly excellent low fuel permeability, have high rigidity, and when used alone to make a single-layer tube, the tube has poor flexibility and is vulnerable to impacts, particularly at low temperatures, and is prone to tube cracking. In order to solve this problem, the thickness of the aromatic polyamide resin layer is reduced and an aliphatic polyamide resin,
A laminated tube having an outer layer made of a thermoplastic resin with excellent flexibility, such as a polyethylene resin, has been studied. However, since aromatic polyamide resin has poor adhesion to other materials, lamination of the inner layer and the outer layer usually requires an adhesive layer at the interface between the two layers. This causes problems such as the manufacturing process becoming more complicated due to the adhesive layer, and the tube weight increasing. In addition, when a low molecular weight fatty acid salt is used in the composition of the inner layer for adhesion, the cleavage reaction of the amide bond of the polyamide resin proceeds, which causes problems such as a decrease in resin strength.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel tube which is excellent in low fuel permeability and also in interlayer adhesion, and a method for producing the same.

In order to achieve the above object, a first gist of the present invention is a fuel tube comprising a tubular inner layer made of a composition mainly composed of an aromatic polyamide resin, and an outer layer provided in contact with the outer peripheral surface of the inner layer and made of a composition mainly composed of an aliphatic polyamide resin, wherein the inner layer contains a fatty acid amide compound obtained by dehydration condensation of the following components (A) and (B), and the inner layer and the outer layer are interlaminarly bonded:
(A) a saturated aliphatic monocarboxylic acid having 18 to 50 carbon atoms (B) a diamine having 2 to 21 carbon atoms

The present invention also provides a tubular tube having an inner layer made of a composition containing an aromatic polyamide resin as a main component,
and an outer layer provided in contact with the outer peripheral surface of the tube and made of a composition mainly composed of an aliphatic polyamide resin, the inner layer containing, in addition to the above-mentioned components (A) and (B), a fatty acid amide compound obtained by dehydration condensation of the following component (C), and the inner layer and the outer layer are interlayer-bonded.
(C) Polybasic acid having 2 to 14 carbon atoms

A third aspect of the present invention is a fuel tube comprising a tubular inner layer made of a composition mainly composed of an aromatic polyamide resin, and an outer layer provided in contact with the outer peripheral surface of the inner layer and made of a composition mainly composed of an aliphatic polyamide resin, wherein the inner layer contains a specific fatty acid amide compound having an alicyclic structure, and the inner layer and the outer layer are interlayer-bonded.

A fourth aspect of the present invention is a method for producing a fuel tube according to any one of the first to third aspects, comprising co-extruding, by melt extrusion molding, a composition containing as a main component an aromatic polyamide resin for forming the inner layer and a composition containing as a main component an aliphatic polyamide resin for forming the outer layer.

That is, the present inventors have conducted extensive research to solve the above problems. They have conducted extensive research on a laminated tube having an outer layer made of an aliphatic polyamide resin such as PA12 around an inner layer made of an aromatic polyamide resin such as PA9T, which has excellent low fuel permeability, and have focused on improving the interlayer adhesion between the inner layer and the outer layer. In the course of their research, they have found that the poor interlayer adhesion between the inner layer and the outer layer in the laminated tube is due to the following:
It was discovered that one of the reasons for this is that due to the difference in the linear expansion coefficients of the aliphatic polyamide resin, which is the outer layer material, and the aromatic polyamide resin, which is the inner layer material, even if they are adhered when hot-melted, physical tiny voids occur after cooling.As a result of further research, the inventors found that by incorporating a specific fatty acid amide compound into the inner layer material, the specific fatty acid amide compound bleeds out to the surface of the aromatic polyamide resin, which is the inner layer material, and the saturated aliphatic portion of the specific fatty acid amide compound bonds with the aliphatic polyamide resin, which is the outer layer material, through hydrogen bonds, and the amide bond portion of the specific fatty acid amide compound bonds with the aromatic polyamide resin, which is the inner layer material, through hydrogen bonds, thereby suppressing the occurrence of physical tiny voids after cooling.
It was found that the desired interlayer adhesive strength can be obtained by this method, and the present invention was completed.

As described above, the fuel tube of the present invention comprises a tubular inner layer made of a resin composition mainly composed of an aromatic polyamide resin such as PA9T, and an outer layer made of a resin composition mainly composed of an aliphatic polyamide resin, and the resin composition for forming the inner layer contains a specific fatty acid amide compound. Therefore, the fuel hose of the present invention has high interlayer adhesion, is lightweight, has excellent low fuel permeability, and is also excellent in flexibility, low-temperature impact resistance, and heat resistance. In addition, the fuel tube of the present invention can bond its layers without adhesive, and the material cost is low, so that it can achieve low cost despite the high performance as described above.

Furthermore, if an innermost layer made of a fluorine-based resin is further provided on the inner peripheral surface of the inner layer, the fuel permeability is further improved.

The fuel tube is formed by co-extruding a resin composition for forming the inner layer and a resin composition for forming the outer layer by melt extrusion molding, and interlayer bonding is achieved without the use of adhesives due to the action of a specific fatty acid amide compound in the inner layer material.

FIG. 1 is a diagram showing a configuration of an example of a fuel tube of the present invention.

Next, we will explain an embodiment of the present invention.

The fuel hose of the present invention is, for example, as shown in FIG.
The outer layer 2 is laminated on the outer peripheral surface of the core.
The tube-shaped inner layer 1 is made of a composition mainly composed of an aromatic polyamide resin, and an outer layer 2 is provided in contact with the outer peripheral surface of the inner layer 1 and made of a composition mainly composed of an aliphatic polyamide resin. The inner layer 1 contains a fatty acid amide compound obtained by dehydration condensation of the following components (A) and (B), and the inner layer and the outer layer are bonded to each other.
The "major components" of the aromatic polyamide resin and the aliphatic polyamide resin mentioned above are those that have a large effect on the properties of the entire resin composition, and in the present invention, these mean 50% by weight or more of the entire composition.
(A) a saturated aliphatic monocarboxylic acid having 18 to 50 carbon atoms (B) a diamine having 2 to 21 carbon atoms

The present invention also has a tubular inner layer 1 made of a composition mainly composed of an aromatic polyamide resin, and an outer layer 2 provided in contact with the outer peripheral surface of the inner layer 1 and made of a composition mainly composed of an aliphatic polyamide resin, wherein the inner layer 1 contains, in addition to the above-mentioned components (A) and (B), a fatty acid amide compound obtained by dehydrating and condensing the following component (C), and the inner layer and the outer layer are bonded to each other.
(C) Polybasic acid having 2 to 14 carbon atoms

The present invention further comprises a tubular inner layer 1 made of a composition mainly composed of an aromatic polyamide resin, and an outer layer 2 made of a composition mainly composed of an aliphatic polyamide resin provided in contact with the outer peripheral surface of the inner layer 1,
The inner layer 1 contains a specific fatty acid amide compound, the fatty acid amide compound has an alicyclic structure, and the inner layer 1 and the outer layer 2 are bonded to each other.

Examples of aromatic polyamide resins used as a material for forming the inner layer 1 include polyamide 4T (PA4T), polyamide 6T (PA6T), polyamide MXD6 (PAMXD6), and polyamide MXD6 (PAMXD6).
D6), Polyamide 9T (PA9T), Polyamide 10T (PA10T), Polyamide 1
1T (PA11T), Polyamide 12T (PA12T), Polyamide 13T (PA13T
These may be used alone or in combination of two or more. Among these, PA9T is preferably used from the viewpoints of flexibility and barrier properties.

As described above, the material for the inner layer 1 contains a fatty acid amide compound obtained by dehydrating and condensing a saturated aliphatic monocarboxylic acid having 18 to 50 carbon atoms and a diamine having 2 to 21 carbon atoms.
The saturated aliphatic monocarboxylic acid is a saturated aliphatic monocarboxylic acid having a carbon number of 1 to 30. That is, if the carbon number of the saturated aliphatic monocarboxylic acid and the diamine is less than the above range, the hydrogen bond with the aliphatic polyamide resin becomes weak, and conversely, if the carbon number exceeds the above range, bleeding out from the aromatic polyamide proceeds excessively. Specific examples of the saturated aliphatic monocarboxylic acid include unsubstituted saturated aliphatic monocarboxylic acids such as stearic acid, tricosyl acid, lignoceric acid, pentacosyl acid, nervonic acid, cerotic acid, montanic acid, melissic acid, and other commercially available compounds having a primary carboxyl group on a linear alkyl group having a carbon number of 18 to 50. These are used alone or in combination of two or more kinds. Among the saturated aliphatic monocarboxylic acids, montanic acid is preferably used because of its excellent hydrogen bond with the aliphatic polyamide.
The diamine having 2 to 21 carbon atoms is preferably a diamine having 2 to 10 carbon atoms. That is, if the carbon numbers of the saturated aliphatic monocarboxylic acid and the diamine are less than the above range, the hydrogen bond with the aromatic polyamide resin becomes weak. On the other hand, if the carbon numbers exceed the above range,
This is because the compatibility with aromatic polyamide resins decreases. Specific examples of the diamine include, for example, ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, hexamethylenediamine, metaxylenediamine, tolylenediamine, paraxylenediamine, phenylenediamine, isophoronediamine, 1,10-decanediamine, 1,1
2-dodecanediamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,3-bisaminomethylcyclohexane, 1,4
-bisaminomethylcyclohexane, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, bicyclo[2.2.1]heptane-2,3-diyldimethanamine, 4,4
Among them, alicyclic diamines are more preferable. Examples of the alicyclic diamine include:
1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, bicyclo[2.2.1]heptane-2,3-diyldimethanamine, 4,4-diaminodicyclohexylmethane, 4,4'-methylenebis(2-methylcyclohexylamine), 2,2'-
An example is dimethyl-4,4'-methylenebis(cyclohexan-1-ylamine).
These may be used alone or in combination of two or more. Among the above diamines, 1,3-bisaminomethylcyclohexane is preferably used because of its excellent hydrogen bonding with aromatic polyamides.

Furthermore, as described above, the material for the inner layer 1 contains a fatty acid amide compound obtained by dehydrating and condensing a polybasic acid having 2 to 14 carbon atoms, in addition to a saturated aliphatic monocarboxylic acid having 18 to 50 carbon atoms and a diamine component having 2 to 21 carbon atoms. A polybasic acid having 2 to 10 carbon atoms is preferable. That is, if the carbon number of the polybasic acid is less than the above range, the hydrogen bond with the aliphatic polyamide resin becomes weak, and conversely, if the carbon number exceeds the above range, bleeding out from the aromatic polyamide proceeds excessively. Specific examples of the polybasic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid,
Examples of the aromatic dicarboxylic acid include azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, and dimer acid. Examples of the aromatic dicarboxylic acid include phthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. Among these, alicyclic dicarboxylic acids are more preferred.
Examples of alicyclic dicarboxylic acids include 1,1-cyclopropanedicarboxylic acid, 1,2-cyclopropanedicarboxylic acid, 1,1-cyclobutanedicarboxylic acid, 1,2-cyclobutanedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, 3,4-diphenyl-1,2-cyclobutanedicarboxylic acid, 2,4-diphenyl-1,3-cyclobutanedicarboxylic acid, 3,4-bis(2-hydroxyphenyl)-1,2-cyclobutanedicarboxylic acid, 2,4-bis(2-
hydroxyphenyl)-1,3-cyclobutanedicarboxylic acid, 1-cyclobutene-1,2
-dicarboxylic acid, 1-cyclobutene-3,4-dicarboxylic acid, 1,1-cyclopentanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,
4-Cyclohexanedicarboxylic acid, 1-cyclohexene-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 1,4-(2-norbornene)dicarboxylic acid, 2
,3-norbornane dicarboxylic acid, 3-methyl-4-cyclohexene-1,2-dicarboxylic acid, 4-methyl-4-cyclohexene-1,2-dicarboxylic acid, spiro[3.3]heptane-2,6-dicarboxylic acid, 1,1-cyclohexane diacetic acid, 1,4-cyclohexane diacetic acid, cis-1,2,2-trimethyl-1,3-cyclopentane dicarboxylic acid, bicyclo[2.2.2]octane-1,4-dicarboxylic acid, bicyclo[2.2.2]octane-2,3-dicarboxylic acid, 2,5-dioxo-1,4-bicyclo[2.2.2]octane dicarboxylic acid, 1,3-adamantane dicarboxylic acid, 4,8-dioxo-1,3-adamantane dicarboxylic acid, 2,6-decalin dicarboxylic acid, 1,5-decalin dicarboxylic acid,
Examples of the polybasic acids include 1,6-decalindicarboxylic acid, 2,3-decalindicarboxylic acid, 2,7-decalindicarboxylic acid, and 1,3-adamantanediacetic acid. These may be used alone or in combination of two or more. Among the above polybasic acids, 1,1-cyclohexanediacetic acid is preferably used because of its excellent adhesiveness to aliphatic polyamide resins.

The content of the fatty acid amide compound in the composition mainly composed of an aromatic polyamide resin, which is the material for the inner layer 1, is preferably in the range of 0.05 to 5% by weight, more preferably in the range of 0.1 to 1% by weight. That is, if the content is less than the above range, the desired interlayer adhesive effect due to the fatty acid amide compound cannot be obtained, and conversely, if the content exceeds the above range, the fatty acid amide compound is excessively unevenly distributed in the vicinity of the adhesive interface, and in this case too, the desired interlayer adhesive effect cannot be obtained.

Examples of the aliphatic polyamide resin used as the material for forming the outer layer 2 include polyamide 46 (PA46), polyamide 6 (PA6), polyamide 66 (PA66), polyamide 99 (PA99), polyamide 610 (PA610), and polyamide 612 (PA6
12), Polyamide 11 (PA11), Polyamide 912 (PA912), Polyamide 1
2 (PA12), a copolymer of polyamide 6 and polyamide 66 (PA6/66), a copolymer of polyamide 6 and polyamide 12 (PA6/12), etc. These may be used alone or in combination of two or more kinds.

In addition, the above-mentioned materials for the inner layer 1 and the materials for the outer layer 2 may contain, as necessary, pigments such as carbon black and titanium oxide, fillers such as calcium carbonate, plasticizers such as fatty acid esters, mineral oils and butylbenzenesulfonamide, antioxidants such as hindered phenol-based antioxidants and phosphorus-based heat stabilizers, heat-resistant anti-aging agents, impact resistance agents such as α-polyolefins, ultraviolet inhibitors, antistatic agents, reinforcing agents such as organic fibers, glass fibers, carbon fibers and metal whiskers, flame retardants and the like, in addition to the resins that are the main components thereof and the specific fatty acid amide compounds added thereto.

The fuel hose of the present invention shown in FIG. 1 can be produced, for example, as follows. That is, the materials for the inner layer 1 and the outer layer 2 as described above are prepared, and the materials for forming each layer are melt-kneaded (the inner layer material is 260 to 330° C., the outer layer material is 200 to 250° C.) using, for example, an extrusion molding machine (a multi-layer extrusion molding machine manufactured by Plastics Engineering Research Institute).
By co-extrusion molding while mixing at 100° C. and passing the co-extruded molten tube through a sizing die, a fuel hose having a two-layer structure in which the outer layer 2 is formed on the outer peripheral surface of the inner layer 1 can be produced.
The specific fatty acid amide compound in the material acts to ensure good adhesion between the two layers.

When the hose is to be formed into a bellows shape, the above-mentioned co-extruded molten tube can be passed through a corrugating machine to produce a bellows-shaped hose of a desired dimension.

In the fuel hose of the present invention thus obtained, the inner diameter of the hose is preferably within a range of 1 to 40 mm, and more preferably within a range of 2 to 36 mm, and the outer diameter of the hose is preferably within a range of 2 to 44
The thickness of the inner layer 1 is preferably in the range of 0.02 to 1.0 mm, and more preferably in the range of 0.05 to 0.6 mm.
The thickness of the outer layer 2 is preferably within a range of 0.03 to 1.5 mm, and particularly preferably within a range of 0.05 to 1.0 mm.

It should be noted that the fuel hose of the present invention is not limited to the two-layer structure as shown in FIG. 1 . For example, it may be formed into a three-layer structure in which an innermost layer is formed on the inner peripheral surface of the inner layer 1.

The innermost layer is preferably made of a fluororesin, since the fuel hose of the present invention has a better low fuel permeability. Examples of the fluororesin include polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (CTFE), polytetrafluoroethylene (PTFE),
Tetrafluoroethylene-hexafluoro copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-
Examples of such materials include copolymers such as hexafluoropropylene-vinylidene fluoride copolymer (THV), copolymer of ethylene and tetrafluoroethylene (ETFE), copolymer of ethylene and polychlorotrifluoroethylene (ECTFE), modified copolymers thereof, various graft polymers and blends thereof, and further conductive fluororesins to which carbon black, carbon fiber, carbon nanotubes, conductive polymers or the like have been added to impart conductivity.
These may be used alone or in combination of two or more.

The fuel hose of the present invention, in which an innermost layer is formed on the inner peripheral surface of the inner layer 1, can be produced, for example, as follows. That is, the material for the innermost layer is prepared together with the material for the inner layer 1 and the material for the outer layer 2, and the innermost layer is formed by combining the inner layer 1 and the outer layer 2 in the above-mentioned manufacturing method.
Alternatively, a separate extrusion molding machine for the innermost layer is used to extrude the innermost layer onto the inner surface of the inner layer 1 formed by the above-mentioned manufacturing method, and the molten tube thus obtained is passed through a sizing die, thereby producing a fuel hose in which the innermost layer is formed on the inner surface of the inner layer 1.

In the fuel hose of the present invention, the thickness of the innermost layer is preferably within a range of 0.03 to 0.5 mm, and particularly preferably within a range of 0.05 to 0.3 mm. In the fuel hose of the present invention constituting the innermost layer, the suitable ranges of the thicknesses of the inner layer 1 and outer layer 2, and the inner and outer diameters of the hose are as described above.

Furthermore, the fuel hose of the present invention may have a structure in which, for example, an outermost layer made of an appropriate material is formed around the outer periphery of the outer layer 2, as required.

The fuel hose of the present invention is capable of handling gasoline, alcohol-mixed gasoline, diesel fuel, CN
The present invention is preferably used as a hose for transporting automobile fuels such as compressed natural gas (G) and liquefied petroleum gas (LPG), but is not limited thereto. It can also be used as a hose for transporting fuels such as methanol, hydrogen, and dimethyl ether (DME) for fuel cell automobiles.

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

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

[PA9T]
Genestar N1001A (melting point: 304°C), manufactured by Kuraray Co., Ltd.

[PA6T]
Arlen AE4200, manufactured by Mitsui Chemicals

[MXD6]
Reny S6007, manufactured by Mitsubishi Gas Chemical Company, Inc.

[Fatty acid amide compound (i)]
Slipax E (ethylene bisstearic acid amide, saturated aliphatic monocarboxylic acid with 18 carbon atoms/diamine with 2 carbon atoms), manufactured by Mitsubishi Chemical Corporation

[Fatty acid amide compound (ii)]
Slipax ZHB (hexamethylene bisbehenamide, saturated fatty acid monocarboxylic acid with 22 carbon atoms/diamine with 6 carbon atoms), manufactured by Mitsubishi Chemical Corporation

[Fatty acid amide compound (iii)]
A reaction vessel equipped with a stirrer, a thermometer, and a water divider was charged with 850 parts by mass of montanic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a monocarboxylic acid and 2 parts by mass of maleic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a dicarboxylic acid.
300 parts by mass of hexamethylenediamine (manufactured by Wako Pure Chemical Industries, Ltd.) as a diamine were added, and a condensation reaction was carried out while dehydrating under a nitrogen atmosphere at 180 to 220° C. for 3 to 5 hours, followed by amidation and cooling to room temperature to obtain fatty acid amide compound (iii).

[Fatty acid amide compound (iv)]
A reaction vessel equipped with a stirrer, a thermometer, and a water divider was charged with 850 parts by mass of montanic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as an aliphatic monocarboxylic acid, 200 parts by mass of 1,1-cyclohexanediacetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as an alicyclic dicarboxylic acid, and 300 parts by mass of 1,3-bisaminomethylcyclohexane (manufactured by Wako Pure Chemical Industries, Ltd.) as an alicyclic diamine, and the mixture was stirred for 18 hours under a nitrogen atmosphere.
The mixture was amidated by carrying out a condensation reaction while dehydrating at 0 to 220° C. for 3 to 5 hours, and then cooled to room temperature to obtain a fatty acid amide compound (iv).

[Saturated Aliphatic Metal Salts]
Zinc stearate, manufactured by Wako Pure Chemical Industries, Ltd.

[PA12]
Rilsan AESN NOIR P20TL, manufactured by Arkema

[Impact resistance agent]
Tafmer A-4085 (α-polyolefin), manufactured by Mitsui Chemicals

[Plasticizer]
Butylbenzenesulfonamide, manufactured by Wako Pure Chemical Industries, Ltd.

[Heat-resistant anti-aging agent]
Irganox 1010, manufactured by Ciba Japan

[Fluororesin]
Neoflon RP5000, manufactured by Daikin Industries, Ltd.

Next, a hose was made using the above materials as shown below.

[Examples 1 to 10, Comparative Examples 1 and 2]
The innermost layer material (only Examples 9 and 10), inner layer material, and outer layer material shown in Tables 1 to 3 below were prepared, and these were extruded in an extrusion molding machine (a multi-layer extrusion molding machine manufactured by Plastics Engineering Research Institute Co., Ltd.).
The mixture was melt-kneaded using the above mixture and co-extruded to prepare a smooth hose having an inner diameter of 6 mm.
In addition, when the smooth hose prepared above has a two-layer structure, the thickness of the inner layer is 0.3 mm and the thickness of the outer layer is 0.
.7 mm, and in the case of a three-layer structure, the thickness of the innermost layer is 0.05 mm, the thickness of the inner layer is 0.25 mm,
The thickness of the outer layer was 0.7 mm.

Using the thus obtained hoses of the Examples and Comparative Examples, the properties were evaluated according to the following criteria.

[Fuel permeation amount]
For each hose, a pressure-equalizing hose permeability measuring device (GTR-TUBE, manufactured by GTR Tech Co., Ltd.)
The permeability coefficient of simulated alcohol-added gasoline, which was a mixture of toluene, isooctane, and ethanol in a volume ratio of 45:45:10, was measured at 40°C for one month using a 3-TG (unit: mg/m/day). The values shown in the table are the values when equilibrium was reached. Values less than 50 (mg/m/day) are indicated as ○, values over 50 (mg/m/day) are indicated as ◯, and values over 50 (mg/m/day) are indicated as ◯.
y) or more was evaluated as x.

[Interlayer Adhesion Strength]
Each hose was cut into a strip with a width of 10 mm to prepare a sample. Then, the interlayers of each sample (in Examples 1 to 10 and Comparative Examples 1 and 2, the inner layer/outer layer; in Examples 15 to 20,
In the test, the innermost layer/inner layer and the inner layer/outer layer were peeled off, and each was clamped in the chuck of a tensile tester, and the 180° peel strength (N/cm) was measured at a pulling speed of 50 mm/min. If the peel strength was 25 N/cm or more, the target value was set to indicate that the interlayer adhesion was good, and the evaluation was expressed as ○, if it was 20 N/cm or more but less than 25 N/cm, it was expressed as △, and if it was 20 N/cm or more but less than 25 N/cm, it was expressed as △.
In the present invention, an evaluation of △ or higher (◯, △) is required.

From the above results, it is evident that all of the examples have a small amount of fuel permeation and are excellent in interlayer adhesion.

In contrast, the product of Comparative Example 1 has a laminated structure of a PA9T inner layer and a PA12 outer layer, like the product of the Example, but the material of the inner layer does not contain a specific fatty acid amide compound, and the interlayer adhesion like that of the product of the Example is not obtained. The product of Comparative Example 2 could not be molded because the inner layer was foamed.

The fuel hose of the present invention is capable of handling gasoline, alcohol-mixed gasoline, diesel fuel, CN
The hose can be suitably used as a transport hose for automobile fuels such as compressed natural gas (G), liquefied petroleum gas (LPG), etc.

1 Inner layer 2 Outer layer

Claims (6)

A fuel tube comprising: a tubular inner layer made of a composition mainly composed of an aromatic polyamide resin; and an outer layer provided in contact with the outer peripheral surface of the inner layer and made of a composition mainly composed of an aliphatic polyamide resin, wherein the inner layer contains a fatty acid amide compound obtained by dehydration condensation of the following components (A), (B) and (C), the content of the fatty acid amide compound in the composition mainly composed of the aromatic polyamide resin is in the range of 0.05 to 5% by weight, and the inner layer and the outer layer are interlaminarly bonded.
(A) a saturated aliphatic monocarboxylic acid having 18 to 50 carbon atoms; (B) a diamine having 2 to 21 carbon atoms; and (C) a polybasic acid having 2 to 14 carbon atoms. A fuel tube comprising: a tubular inner layer made of a composition mainly composed of an aromatic polyamide resin; and an outer layer provided in contact with the outer peripheral surface of the inner layer and made of a composition mainly composed of an aliphatic polyamide resin, the inner layer being obtained by dehydration condensation of the following components (A) and (B) and containing a fatty acid amide compound having an alicyclic structure, the content of the fatty acid amide compound in the composition mainly composed of the aromatic polyamide resin being in the range of 0.05 to 5% by weight, and the inner layer and the outer layer being interlaminarly bonded.
(A) a saturated aliphatic monocarboxylic acid having 18 to 50 carbon atoms (B) a diamine having 2 to 21 carbon atoms 3. The fuel tube according to claim 2, wherein the fatty acid amide compound is a fatty acid amide compound obtained by dehydration condensation of the following component (C) in addition to the components (A) and (B):
(C) Polybasic acid having 2 to 14 carbon atoms The fuel tube according to any one of claims 1 to 3, wherein the main component of the aromatic polyamide resin composition is polyamide 9T (PA9T). 5. The fuel tube according to claim 1, further comprising an innermost layer made of a fluorine-based resin on an inner peripheral surface of the inner layer. 6. A method for producing the fuel tube according to claim 1 , comprising co-extruding, by melt extrusion, a composition containing as a main component an aromatic polyamide resin for forming the inner layer and a composition containing as a main component an aliphatic polyamide resin for forming the outer layer.

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