Fuel transport hose

Abstract

To provide a fuel transport hose capable of suppressing elution of sulfur into a transported object, and suppressing inter-layer peeling of a hose.SOLUTION: A fuel transport hose of the present invention is a fuel transport hose in which an inner layer, an intermediate layer, a reinforcing layer, and an outer layer are laminated in this order. The inner layer contains a thermoplastic resin composition containing a first thermoplastic resin having a deflection temperature under load of 75°C or higher, and a second thermoplastic resin having a deflection temperature under load of less than 75°C. The intermediate layer contains a rubber composition containing nitrile rubber. The inner layer and the intermediate layer (LB) are bonded directly or via an adhesive layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a fuel transport hose. More specifically, the present disclosure relates to a hose for transporting fuels such as gasoline, light oil, kerosene, and liquefied petroleum gas.

Background Art

[0002] A hose for transporting fuel or the like may have a layer of vulcanized rubber on the inner side.

[0003] Patent Document 1 discloses a low gas permeability hose comprising an inner layer, a reinforcing layer and an outer layer, wherein the inner layer has an innermost water-resistant layer made of vulcanized rubber, and a gas barrier layer formed on the outer surface side of the water-resistant layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a fuel transport hose that can suppress elution of sulfur into a transported material and can suppress interlayer peeling of the hose.

Means for Solving the Problems

[0006] The present inventors have found that the above problems can be achieved by the following means: 《Aspect 1》 A fuel transport hose in which an inner layer, an intermediate layer, a reinforcing layer, and an outer layer are laminated in this order, The inner layer contains a thermoplastic resin composition containing a first thermoplastic resin having a deflection temperature under load of 75°C or higher, and a second thermoplastic resin having a deflection temperature under load of lower than 75°C, The aforementioned intermediate layer contains a rubber composition containing acrylonitrile-butadiene rubber. The inner layer and the intermediate layer are bonded together directly or via an adhesive layer. Fuel transport hose. 《Aspect 2》 The fuel transport hose according to embodiment 1, wherein the mass ratio of the first thermoplastic resin to the total of the first thermoplastic resin and the second thermoplastic resin is 0.05 to 0.95. 《Aspect 3》 The fuel transport hose according to embodiment 1 or 2, wherein the first thermoplastic resin has aromatic rings in its main chain. Appearance 4 The fuel transport hose according to embodiment 3, wherein the aromatic ring has 6 to 10 carbon atoms. 《Aspect 5》 The fuel transport hose according to any one of embodiments 1 to 4, wherein the first thermoplastic resin is an aromatic polyamide resin. 《Aspect 6》 The fuel transport hose according to any one of embodiments 1 to 5, wherein the second thermoplastic resin is an aliphatic polyamide. Appearance 7 The fuel transport hose according to any one of embodiments 1 to 6, wherein the inner layer contains 1.0% by mass or less of free sulfur components, or does not contain free sulfur components. 《Aspect 8》 A fuel transport hose according to any one of embodiments 1 to 7, wherein the ratio of the thickness of the inner layer to the thickness of the intermediate layer is 0.01 to 2.00. 《Aspect 9》 The aforementioned inner layer has a swelling degree of 35.0% or less after being immersed in fuel at a temperature of 23°C for 7 days. The fuel contains 42.5% by volume of isooctane, 42.5% by volume of toluene, and 15% by volume of ethanol relative to the total amount of fuel. A fuel transport hose as described in any one of embodiments 1 to 8. 《Aspect 10》 The aforementioned inner layer exhibits a fuel permeability of 5.00 mg·mm / 24h·cm after being immersed in fuel at 23°C for 7 days. 2is as follows, The fuel contains 42.5% by volume of isooctane, 42.5% by volume of toluene, and 15% by volume of ethanol relative to the entire fuel, The fuel transport hose according to any one of aspects 1 to 9. (Aspect 11) The fuel transport hose according to any one of aspects 1 to 10, wherein the inner layer has a storage elastic modulus E at -30°C of 1500 to 3500 MPa. (Aspect 12) The fuel transport hose according to any one of aspects 1 to 11, wherein the inner layer further contains rubber and / or an elastomer. (Aspect 13) The fuel transport hose according to aspect 12, wherein the elastomer is a polyester elastomer, a polyamide elastomer, or a modified styrene-based elastomer. (Aspect 14) The fuel transport hose according to aspect 12 or 13, wherein the inner layer has a sea-island structure of the thermoplastic resin composition and the rubber and / or elastomer. (Aspect 15) The fuel transport hose according to any one of aspects 1 to 14, wherein the acrylonitrile-butadiene rubber contained in the intermediate layer contains 25 to 50% by mass of acrylonitrile relative to the acrylonitrile-butadiene rubber. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a fuel transport hose that can suppress elution of sulfur into the transported object and suppress interlayer peeling of the hose. [Brief Description of the Drawings]

[0008] [Figure 1] Figure 1 is a schematic side view of a fuel transport hose 10 according to the first embodiment of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view of the fuel transport hose 10 according to the first embodiment of the present invention. Detailed Description of the Embodiments

[0009] Hereinafter, embodiments of the present disclosure will be described in detail. It should be noted that the present disclosure is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist of the disclosure.

[0010] The fuel transport hose of the present invention is a fuel transport hose in which an inner layer, an intermediate layer, a reinforcing layer, and an outer layer are laminated in this order, wherein the inner layer contains a thermoplastic resin composition comprising a first thermoplastic resin having a deflection temperature under load of 75°C or higher and a second thermoplastic resin having a deflection temperature under load of lower than 75°C, the intermediate layer contains a rubber composition comprising a vulcanized rubber, and the inner layer and the intermediate layer are bonded directly or via an adhesive layer.

[0011] Here, that the inner layer, the intermediate layer, the reinforcing layer, and the outer layer are laminated in this order means that these layers are laminated in this order from the inner side to the outer side of the fuel transport hose.

[0012] Generally, fuel transport hoses employ a layer containing a vulcanized rubber composition as their inner layer. When transporting materials such as fuel using such fuel transport hoses, some of the sulfur or sulfur compounds added to the rubber composition may leach into the transported material. From the viewpoint of suppressing such leaching of sulfur components, it is conceivable to place an inner layer containing a thermoplastic resin composition as a barrier layer on the innermost part of the fuel transport hose. Adhesion between the inner layer and the layer containing the rubber composition, i.e., the intermediate layer, is thought to increase adhesive strength as the thermoplastic resin composition and the rubber composition soften or flow due to the heat during vulcanization, promoting contact and entanglement at the interface. However, depending on the composition of the thermoplastic resin composition, it may not soften or flow easily, resulting in insufficient adhesion. In fuel transport hoses with insufficient adhesion, repeated or large deformations can cause delamination between the inner layer and the intermediate layer. Furthermore, depending on the composition of the thermoplastic resin composition, it may soften or flow significantly during vulcanization, and the flow and deformation of the rubber composition may cause problems such as uneven thickness of the inner layer.

[0013] While not limited by principle, if the deflection temperature under load of the thermoplastic resin composition is high, repeated or significant deformation of the hose after vulcanization is likely to cause delamination between the inner layer and the intermediate layer. On the other hand, if the deflection temperature under load of the thermoplastic resin composition is low, when the rubber composition is vulcanized, the inner layer is likely to deform in accordance with the deformation of the intermediate layer, resulting in an uneven thickness of the inner layer.

[0014] The fuel transport hose of the present invention contains a thermoplastic resin composition in which the inner layer contains a first thermoplastic resin with a load deflection temperature of 75°C or higher and a second thermoplastic resin with a load deflection temperature of less than 75°C. As a result, even when the rubber composition is vulcanized, the thickness of the inner layer does not change easily, and the adhesion between the inner layer and the intermediate layer is also excellent.

[0015] Figures 1 and 2 are schematic diagrams of a fuel transport hose 10 according to a first embodiment of the present invention. Here, Figure 1 is a side view of the fuel transport hose 10 according to a first embodiment of the present invention, and Figure 2 is a radial cross-sectional view of the fuel transport hose 10 according to a first embodiment of the present invention. Note that neither Figure 1 nor 2 is intended to limit the present invention.

[0016] As shown in Figures 1 and 2, the fuel transport hose 10 according to the first embodiment of the present invention is a fuel transport hose 10 in which an inner layer 11, an intermediate layer 12, a reinforcing layer 13, and an outer layer 14 are laminated in this order. Here, "laminated in this order" means that each layer is laminated in this order from the inside of the fuel transport hose 10, i.e., from the inside of the hose 15 to the outside of the fuel transport hose 10.

[0017] The inner layer 11 contains a thermoplastic resin composition comprising a first thermoplastic resin having a load deflection temperature of 75°C or higher, and a second thermoplastic resin having a load deflection temperature of less than 75°C. The intermediate layer 12 contains a rubber composition containing vulcanized rubber. The inner layer 11 and the intermediate layer 12 are bonded together directly or via an adhesive layer (not shown).

[0018] Inner layer The inner layer contains a thermoplastic resin composition and optionally other components, such as a flexibility component.

[0019] In a fuel transport hose, by arranging an inner layer containing a thermoplastic resin composition on the inner diameter side of an intermediate layer containing a vulcanized rubber composition, the leaching of sulfur components from the intermediate layer into the transported material, such as fuel, can be suppressed.

[0020] The inner layer preferably contains 1.0% by mass or less of free sulfur components, or preferably contains no free sulfur components at all.

[0021] The less free sulfur components the inner layer contains, the more effectively the leaching of sulfur components into transported materials such as fuel can be suppressed. Therefore, a lower amount of free sulfur components in the inner layer is preferable.

[0022] The inner layer may contain a small amount of free sulfur due to the migration of sulfur or sulfur compounds from the adjacent intermediate layer or adhesive layer, preferably containing 1.0% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.2% by mass or less of free sulfur.

[0023] Here, free sulfur components refer to sulfur or sulfur compounds that can be extracted from the inner layer by the fuel. The amount of free sulfur components contained in the inner layer can be determined by sealing the test fuel inside a hose cut to a predetermined length, leaving it standing in a 23°C atmosphere for 48 hours or more, and then quantifying the sulfur components contained in the test fuel. The sulfur components in the test fuel can be detected, for example, by oxidative decomposition coulometric titration using a commercially available sulfur analyzer, in accordance with JIS K2541-2 Crude oil and petroleum products - Sulfur content test method Part 2 Microcoulometric titration method. Here, the test fuel is a fuel containing 42.5 vol% isooctane, 42.5 vol% toluene, and 15 vol% ethanol in total.

[0024] The ratio of the thickness of the inner layer to the thickness of the intermediate layer is preferably 0.01 to 2.00.

[0025] When the ratio of the inner layer thickness to the intermediate layer thickness is within this range, it is particularly possible to achieve both the variation in the inner layer thickness due to the flow of the intermediate layer rubber composition during vulcanization and the adhesion between the inner layer and the intermediate layer.

[0026] The ratio of the thickness of the inner layer to the thickness of the intermediate layer may be 0.01 to 2.00, 0.10 to 1.80, or 0.50 to 1.40.

[0027] The inner layer preferably has a degree of swelling of 35.0% or less after being immersed in fuel at a temperature of 23°C for 7 days.

[0028] The smaller the degree of swelling of the inner layer is compared to the above value, the more effectively deformation of the inner layer can be suppressed when fuel is transported through the fuel transport hose.

[0029] The above swelling degree may be 35.0-0.0%, 30.0-1.0%, or 15.0-2.0%.

[0030] Furthermore, the inner layer showed a fuel permeability of 5.00 mg·mm / 24h·cm after immersion in fuel at 23°C for 7 days. 2 The following is preferable:

[0031] A lower fuel permeability of the inner layer than the above value is advantageous for fuel transport.

[0032] The fuel permeability values ​​mentioned above are 5.00 to 0.01 mg / mm / 24h / cm². 2 4.50~0.02 mg·mm / 24h·cm 2 3.50~0.10 mg·mm / 24h·cm 2 , or 2.50-0.50 mg / mm / 24h / cm 2 That's fine.

[0033] In this invention, the fuel used to measure the degree of swelling and fuel permeability is a fuel containing 42.5% by volume of isooctane, 42.5% by volume of toluene, and 15% by volume of ethanol relative to the total fuel. However, the fuel that can be transported by the fuel transport hose of this invention is not limited to the above composition.

[0034] The inner layer preferably has a storage modulus E at -30°C of 1,500 to 3,500 MPa.

[0035] If the storage modulus E' at -30°C is within the above range, it is advantageous for the use of fuel transport hoses in low-temperature environments.

[0036] The above storage modulus E' may be 1,500-3,500 MPa, 1,700-3,200 MPa, 2,000-3,000 MPa, or 2,200-2,500 MPa.

[0037] <Thermoplastic resin composition> The thermoplastic resin composition contains a first thermoplastic resin having a load deflection temperature of 75°C or higher, and a second thermoplastic resin having a load deflection temperature of less than 75°C.

[0038] The mass ratio of the first thermoplastic resin to the total mass of the first thermoplastic resin and the second thermoplastic resin is preferably 0.05 to 0.95.

[0039] When the mass ratio of the first thermoplastic resin to the sum of the first and second thermoplastic resins is within this range, it is particularly possible to achieve both the variation in the thickness of the inner layer due to the flow of the intermediate layer rubber composition during vulcanization and the adhesion to the intermediate layer.

[0040] The mass ratio of the first thermoplastic resin to the total mass of the first thermoplastic resin and the second thermoplastic resin may be 0.05 to 0.95, 0.10 to 0.90, 0.20 to 0.80, 0.30 to 0.70, or 0.40 to 0.60.

[0041] (First thermoplastic resin) The first thermoplastic resin is a thermoplastic resin with a load deflection temperature of 75°C or higher.

[0042] Here, the temperature deflection under load can be measured in accordance with JIS K 7191 "Plastics - Test method for temperature deflection under load". A test specimen (80 mm in length, 10 mm in width, and 4 mm in thickness) made using an injection molding machine (Century Innovation Co., Ltd.) is fixed at both ends in the vertical direction, and a load of 1.8 MPa is applied to its center while the temperature is raised at a rate of 2°C / min.

[0043] The load deflection temperature of the first thermoplastic resin may be 75-150°C, 80-140°C, or 90-130°C.

[0044] The first thermoplastic resin preferably has aromatic rings in its main chain. If the thermoplastic resin composition contains a thermoplastic resin that has a load deflection temperature of 75°C or higher and has aromatic rings in its main chain, swelling of the inner layer and changes in physical properties are less likely to occur when it comes into contact with fuel.

[0045] The aromatic ring preferably has 6 to 10 carbon atoms. That is, the aromatic ring may be, for example, a 6-membered ring, an 8-membered ring, or a 10-membered ring.

[0046] The first thermoplastic resin is preferably an aromatic polyamide resin.

[0047] Examples of thermoplastic resins with a load deflection temperature of 75°C or higher include, but are not limited to, nylon MXD6 (MXD6), nylon 6T (Ny6T), nylon 6I (Ny6I), nylon 9T (Ny9T), polybutylene naphthalate (PBN), or polyphenylene sulfide (PPS).

[0048] (Second thermoplastic resin) The second thermoplastic resin is a thermoplastic resin with a load deflection temperature of less than 75°C.

[0049] Here, the load deflection temperature of the second thermoplastic resin can be measured by the same method as the load deflection temperature of the first thermoplastic resin.

[0050] The load deflection temperature of the second thermoplastic resin may be 10 to less than 75°C, 15 to 70°C, 30 to 65°C, or 40 to 60°C.

[0051] The second thermoplastic resin is preferably an aliphatic polyamide. When the thermoplastic resin composition contains an aliphatic polyamide with a load deflection temperature of less than 75°C, it is not too rigid, and the occurrence of cracks in the inner layer due to deformation and repeated fatigue can be suppressed.

[0052] Examples of thermoplastic resins with a deflection temperature of less than 75°C include, but are not limited to, nylon 6 (Ny6), nylon 6.66 (Ny6.66), nylon 6.10 (Ny6.10), nylon 6.12 (Ny6.12), nylon 10.10 (Ny10.10), nylon 11 (Ny11), nylon 12 (Ny12), nylon 66 (Ny66), polybutylene terephthalate (PBT), or ethylene vinyl alcohol copolymer (EVOH). Furthermore, thermoplastic resins with a deflection temperature of less than 75°C may also be copolymers of these resins.

[0053] <Softening ingredients> The inner layer preferably contains rubber and / or elastomer as a flexible component.

[0054] Examples of rubber include, but are not limited to, butyl rubber, ethylene-propylene-diene rubber, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, acrylic rubber, fluororubber, epichlorohydrin rubber, epoxidized natural rubber, or mixtures thereof. The rubber may be vulcanized.

[0055] Examples of elastomers include, but are not limited to, polyester elastomers, polyamide elastomers, polystyrene elastomers, polyolefin elastomers, polyurethane elastomers, or vinyl chloride elastomers and modified versions thereof. Furthermore, polyester elastomers, polyamide elastomers, and polystyrene elastomers are particularly preferred from the viewpoint of being less prone to swelling in fuel and having good affinity with thermoplastic resins.

[0056] If the inner layer contains rubber and / or elastomer, the inner layer may have a sea-island structure of thermoplastic resin composition and rubber and / or elastomer.

[0057] Middle class The intermediate layer contains a rubber composition that includes vulcanized rubber.

[0058] The vulcanized rubber may be rubber that has been vulcanized from acrylonitrile-butadiene rubber (NBR), acrylonitrile-butadiene rubber (NBR) / polyvinyl chloride (PVC) blends, chlorosulfonated polyethylene (CSM), butyl rubber (IIR), or mixtures thereof.

[0059] From the viewpoint of oil resistance, acrylonitrile-butadiene rubber may contain 25 to 50% by mass of acrylonitrile relative to the total amount of acrylonitrile-butadiene rubber. Acrylonitrile-butadiene rubber may contain 25 to 50% by mass, 30 to 45% by mass, or 35 to 40% by mass of acrylonitrile relative to the total amount of acrylonitrile-butadiene rubber.

[0060] The rubber composition may further contain additives such as crosslinking agents, anti-aging agents, plasticizers, processing aids, crosslinking aids, crosslinking accelerators, reinforcing agents (fillers), scorch inhibitors, dilution accelerators, organic modifiers, softeners, and tackifiers.

[0061] 《Adhesive layer》 The adhesive layer is a layer containing any material capable of bonding the inner layer and the intermediate layer.

[0062] The adhesive layer can be, for example, a phenolic resin adhesive, a urethane resin adhesive, an epoxy resin adhesive, a resorcinol resin adhesive, a urea resin adhesive, or a melamine resin adhesive. Examples include modified silicone adhesives.

[0063] Reinforcement The reinforcing layer may have, for example, at least one layer of organic fibers or metal wires.

[0064] The arrangement of the organic fiber layer and the metal wire layer in the reinforcing layer is not particularly limited, but it is preferable that the organic fiber layer is on the inner layer side and the metal wire layer is on the outer layer side, and in particular, that the metal wire layer is on the outermost layer side of the reinforcing layer. This allows the expansion and contraction of the inner layer during use of the fuel transport hose to be buffered by the organic fiber layer on the inner layer side of the reinforcing layer, while high durability is ensured by the metal wire layer on the outer layer side of the reinforcing layer.

[0065] <Organic fiber layer> The organic fiber layer may contain fibers comprising at least one selected from the group consisting of poly(p-phenylenebenzbisoxazole), polyester, polyamide, and polyketone.

[0066] Furthermore, the organic fiber layer may be a layer in which yarn made of organic fibers is woven together. The organic fiber layer has a braided structure or a spiral structure, preferably a braided structure. The braided structure is more elastic than the spiral structure. Therefore, when the organic fiber layer has a braided structure, it is more flexible and easier to handle.

[0067] <Metal wire layer> The metal wire layer may be a layer in which metal wires, such as steel wire, copper and copper alloy wire, aluminum and aluminum alloy wire, magnesium alloy wire, titanium and titanium alloy wire, etc. are braided together. It is particularly preferable that the metal wire layer is a layer in which steel wire is braided together. Examples of steel wires include stainless steel wire or galvanized steel wire.

[0068] The metal wire layer may be a layer having a blade structure or a spiral structure, preferably a blade structure. The blade structure is a braided form that has higher elasticity compared to the spiral structure. Therefore, when the metal wire layer has a blade structure, it has a certain degree of elasticity, thus maintaining ease of handling while having high durability.

[0069] 《Outer layer》 The outer layer typically consists of a rubber composition, a thermoplastic elastomer, or a thermoplastic elastomer composition.

[0070] Rubber compositions are not limited to those described above, but examples include rubbers such as acrylonitrile-butadiene rubber (NBR), acrylonitrile-butadiene rubber (NBR) / polyvinyl chloride (PVC) blends, chlorosulfonated polyethylene (CSM), and butyl rubber (IIR), to which additives such as crosslinking agents, antioxidants, plasticizers, processing aids, crosslinking accelerators, crosslinking accelerators, reinforcing agents (fillers), scorch inhibitors, compounding accelerators, organic modifiers, softeners, and tackifiers are added.

[0071] Examples of thermoplastic elastomers include olefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers, polyamide elastomers, polyester elastomers, and polyurethane elastomers.

[0072] Examples of thermoplastic elastomer compositions include those comprising a matrix containing thermoplastic resins such as polyamide resins, polyester resins, ethylene-vinyl alcohol resins, polyolefin resins, polyketone resins, polyacetal resins, polyphenylene sulfide resins, polyphenylene ether resins, and fluororesins, and domains containing rubber such as butyl rubber, modified butyl rubber, olefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers, ethylene-unsaturated carboxylic acid ester copolymers, polyamide elastomers, polyester elastomers, and polyurethane elastomers.

[0073] The thickness of the outer layer is preferably 0.2 to 5.0 mm, more preferably 0.2 to 4.0 mm, and even more preferably 0.2 to 3.0 mm. [Examples]

[0074] Examples 1-22 and Comparative Examples 1-4 <Making a hose> The first thermoplastic resin, the second thermoplastic resin, and the elastomer, which were dry-blended in the mixing ratios (mass%) shown in Tables 1-1 and 1-2, were extruded onto a mandrel using an extruder to form the inner layer with the thickness (inner layer thickness) shown in Tables 4-1 and 4-2.

[0075] Next, the rubber composition, prepared using a Banbury mixer at the mixing ratio (parts by mass) shown in Table 2, was extruded onto the outside of the inner layer to the thickness (thickness of the intermediate layer) shown in Tables 4-1 and 4-2 to form the intermediate layer.

[0076] A phenolic resin adhesive was applied to the outside of the intermediate layer, and steel wires were braided using a braiding machine to form a reinforcing layer.

[0077] An outer layer was formed by extruding a rubber composition, prepared using a Banbury mixer at the mixing ratio (parts by mass) shown in Table 3, to a thickness of 2.0 mm on the outside of the reinforcing layer.

[0078] Subsequently, steam vulcanization was performed at 143°C for 60 minutes, and the mandrel was removed to produce a hose with an inner diameter of 22.5 ± 0.5 mm and an outer diameter of 31.7 ± 0.5 mm.

[0079] <Measurement of temperature under load deflection> The deflection temperatures under load of the first and second thermoplastic resins used in each example were measured in accordance with JIS K 7191 "Plastics - Test method for deflection temperature under load." Test specimens (80 mm long x 10 mm wide x 4 mm thick) of these resins, manufactured using an injection molding machine (Century Innovation Co., Ltd.), were fixed at both ends, and a load of 1.8 MPa was applied to the center while the temperature was increased at a rate of 2°C / min.

[0080] <Measurement of the degree of swelling of the inner layer, fuel permeability, and storage modulus> (Sample preparation) Using the first thermoplastic resin, the second thermoplastic resin, and an elastomer in the mixing ratios (mass%) shown in Tables 1-1 and 1-2, sheets with the same composition as the inner layer were prepared using a Φ40 mm single-screw extruder with a T-type 550 mm width and T-type die (Plastics Co., Ltd.). The cylinder and die temperatures were set to 240-265°C, and the cooling roll temperature and take-up speed were set to arbitrary conditions to obtain sheets with an average thickness of 0.15-0.20 mm.

[0081] (Measurement of the degree of swelling of the inner layer) The obtained sheets were cut to a size of 1.2 cm in length and 3.0 cm in width, and their specific gravity was calculated using an automatic hydrometer in accordance with JIS K 6258-2016 "Measurement of Volume Change". The measured samples were immersed in a test fuel (isooctane / toluene / ethanol = 42.5 / 42.5 / 15 vol%) for 7 days, and the specific gravity of the immersed samples was calculated using the same procedure. The degree of swelling was calculated from the change in weight before and after immersion.

[0082] (Measurement of fuel permeability) 20 mL of test fuel (isooctane / toluene / ethanol = 42.5 / 42.5 / 15 vol%) was sealed in an aluminum cup used in JIS Z0208 "Test Method for Permeable Humidity of Moisture-Proof Packaging Materials". The resulting sheet was cut out so that the permeable surface was a circle with a diameter of 60 mm and attached to the cup. The cup was left standing at 23°C with the sheet surface facing downwards so that the sheet and the test fuel were in constant contact, and the weight of the cup was measured daily. The fuel permeability was calculated from the weight loss up to 7 days later.

[0083] (Measurement of storage modulus) The obtained sheet was cut to a size of 0.5 cm in length and 10.0 cm in width, and its viscoelasticity was measured at -30°C with dynamic strain of ±0.1%, frequency of 20 Hz, and static strain of 2%.

[0084] <Evaluation of vulcanization resistance> Each hose prepared was cut perpendicular to its longitudinal direction, and the thickness of the inner layer was measured at 30 points on its circumference using an optical microscope. The coefficient of variation (CV value) was then determined. Similar measurements were taken at 5 points along the longitudinal direction of a 10m hose to determine the variability. When expressed as an index with the CV value of Comparative Example 2 set to 100, a value of less than 80 was rated "Excellent," 80 to less than 90 was rated "Good," 90 to less than 98 was rated "Acceptable," and 98 or higher was rated "Unacceptable." The resistance to changes in circumference thickness due to vulcanization was then evaluated.

[0085] <Evaluation of adhesion between the inner and intermediate layers> Each of the fabricated hoses was cut to a predetermined length to create a ring-shaped test piece. The ends of the peeled test piece were fixed to the grips of the testing machine so that the peeling angle was approximately 90°, and the peeling force between the inner layer and the intermediate layer was measured. When the peeling force in the hose of Comparative Example 1 was expressed as an index with 100, a value of 130 or more was classified as "Excellent," 100 or more and less than 130 as "Good," 80 or more and less than 100 as "Acceptable," and less than 80 as "Unacceptable."

[0086] <result> Tables 1-1 and 1-2 show the composition of the inner layer, Table 2 shows the composition of the intermediate layer, and Table 3 shows the composition of the outer layer. Tables 4-1 and 4-2 show the hose composition and test results for each example. Note that in Tables 1-1 and 1-2, "Ny6.66" refers to a copolymer of nylon 6 and nylon 66. Similarly, "Ny6.12," "Ny6.10," etc., are copolymers of two types of nylon.

[0087] [Table 1-1]

[0088] [Table 1-2]

[0089] [Table 2]

[0090] [Table 3]

[0091] [Table 4-1]

[0092] [Table 4-2]

[0093] As shown in Tables 4-1 and 4-2, the hoses of Examples 1 to 22 exhibited both vulcanization resistance and adhesion between the inner and intermediate layers. On the other hand, Comparative Examples 1 to 4 failed to achieve both vulcanization resistance and adhesion between the inner and intermediate layers. [Explanation of symbols]

[0094] 10 Fuel transport hoses 11 Inner Layer 12 Middle Class 13 Reinforcement layer 14 Outer layer 15 Inside the hose

Claims

1. A fuel transport hose having an inner layer, an intermediate layer, a reinforcing layer, and an outer layer stacked in this order, The inner layer contains a thermoplastic resin composition comprising a first thermoplastic resin having a load deflection temperature of 75°C or higher, and a second thermoplastic resin having a load deflection temperature of less than 75°C. The ratio of the mass of the first thermoplastic resin to the total mass of the first thermoplastic resin and the second thermoplastic resin is 0.20 to 0.

60. The first thermoplastic resin is an aromatic polyamide resin. The second thermoplastic resin is an aliphatic polyamide, The aforementioned intermediate layer contains a rubber composition containing vulcanized rubber, The inner layer and the intermediate layer are bonded together directly or via an adhesive layer. The aforementioned inner layer has a swelling degree of 15.0% or less after being immersed in fuel at a temperature of 23°C for 7 days. The aforementioned inner layer has a fuel permeability of 2.50 mg / mm / 24h / cm² or less after being immersed in fuel at a temperature of 23°C for 7 days. The fuel contains 42.5% by volume of isooctane, 42.5% by volume of toluene, and 15% by volume of ethanol, relative to the total amount of fuel. Fuel transport hose.

2. The fuel transport hose according to Claim 1, wherein the inner layer does not contain either rubber or elastomer.

3. The fuel transport hose according to claim 1 or 2, wherein the inner layer contains 1.0% by mass or less of free sulfur components, or does not contain free sulfur components.

4. The fuel transport hose according to any one of claims 1 to 3, wherein the ratio of the thickness of the inner layer to the thickness of the intermediate layer is 0.01 to 2.

00.

5. The fuel transport hose according to any one of claims 1 to 4, wherein the inner layer has a storage modulus E at -30°C of 1,500 to 3,500 MPa.

6. The fuel transport hose according to any one of claims 1 to 5, wherein the vulcanized rubber is a rubber obtained by vulcanizing acrylonitrile-butadiene rubber, and the acrylonitrile-butadiene rubber contains 25 to 50% by mass of acrylonitrile relative to the total amount of acrylonitrile-butadiene rubber.

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