Resin-made inlet pipe and method of producing the pipe

1. A resin-made fuel inlet pipe, comprising:

a tubular inner layer; and

an outer layer laminated on an outer peripheral surface thereof,

wherein:

the inner layer is formed of a resin having fuel resistance;

the outer layer is formed of a resin (A), which comprises a metallocene-based polyethylene comprising a high-density polyethylene (HDPE) and an ionic liquid and which has a tensile elongation at 8 m/s measured by a high-speed tensile test of 200% or more; and

the inner layer and the outer layer are in a substantially non-adherent state.

2. A resin-made fuel inlet pipe according to claim 1 ,

wherein the metallocene-based polyethylene comprises a metallocene-based, linear, low-density polyethylene (LLDPE).

3. A resin-made fuel inlet pipe according to claim 1 ,

wherein a weight mixing ratio of the metallocene-based polyethylene relative to the HDPE is in a range of from 10/90 to 90/10.

4. A resin-made fuel inlet pipe according to claim 1 ,

wherein the ionic liquid comprises at least one selected from the group consisting of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-hexylpyridium chloride, and N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide.

5. A resin-made fuel inlet pipe according to claim 1 ,

wherein a content of the ionic liquid is 0.1 to 5 parts by weight with respect to 100 parts by weight of a total of the metallocene-based polyethylene and the HDPE.

6. A resin-made fuel inlet pipe according to claim 1 ,

wherein a total thickness of a pipe wall is in a range of from 1.0 to 2.8 mm and a thickness of the outer layer is in a range of from 25 to 100% with respect to a thickness of the inner layer.

7. A resin-made fuel inlet pipe according to claim 1 ,

wherein a central portion of the pipe has a bellows structure and end portions of the pipe each have a straight structure.

8. A resin-made fuel inlet pipe according to claim 1 ,

wherein the inner layer comprises one of a polyamide 11 and a polyamide 12.

9. A resin-made fuel inlet pipe according to claim 1 ,

wherein the inner layer comprises a high-density polyethylene (HDPE).

10. A resin-made fuel inlet pipe according to claim 1 ,

wherein the inner layer comprises a polyamide resin, and the resin (A) for forming the outer layer comprises one of a metallocene-based polyethylene, an olefin-based thermoplastic elastomer (TPO), and a polyester-based thermoplastic elastomer (TPEE).

11. A resin-made fuel inlet pipe according to claim 1 ,

wherein the inner layer comprises a polyethylene resin and the resin (A) forming the outer layer comprises a polyurethane-based thermoplastic elastomer (TPU).

12. A method of producing the resin-made fuel inlet pipe according to claim 1 , comprising subjecting a material for an inner layer and a material for an outer layer to co-extrusion to produce a resin-made fuel inlet pipe in which the outer layer is laminated on the outer peripheral surface of the inner layer in a substantially non-adherent state,

wherein:

the inner layer is tubular;

the material for the inner layer comprises a resin having fuel resistance;

the material for the outer layer comprises a resin (A), which is a metallocene-based polyethylene comprising a high-density polyethylene (HDPE) and an ionic liquid and which has a tensile elongation at 8 m/s measured by a high-speed tensile test of 200% or more.

13. A resin-made fuel inlet pipe according to claim 1 , further comprising one or more innermost layers on an inner peripheral surface of the inner layer.

14. A resin-made fuel inlet pipe according to claim 13 ,

wherein a material for forming the innermost layer comprises at least one selected from the group consisting of a thermoplastic fluorine resin (THV) formed of a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene, an ethylene-tetrafluoroethylene copolymer (ETFE), a polyvinylidene fluoride (PVDF), ethylene vinyl alcohol (EVOH), a polyphenylene sulfide (PPS), a polybutylene naphthalate (PBN), and a polybutylene terephthalate (PBT).