Annulated tubular structure intended for transporting fuel into the tank

Abstract

A partially annulated flexible tubular structure located at least partially inside the fuel tank, in particular the gasoline or diesel tank, particularly the gasoline tank, of a vehicle, said structure being capable of being at least partially submerged in said tank and being intended for transporting said fuel into said tank, said tubular structure comprising at least one layer (1) comprising a composition comprising: a. between 39% and 100% by weight, in particular between 41% and 100% by weight, of at least one aliphatic polyamide of formula W/Z, b. between 0% and 4% by weight, and preferably between 0 and 2%, of at least one plasticizer, c. between 0% and 20% of at least one impact modifier, d. between 0% and 37% by weight of at least one additive, the sum of a.+b.+c.+d. being equal to 100% of the total weight of the composition, excluding a fuel transport structure running from the tank to the motor of the vehicle.

Claims

1. A partially annulated flexible tubular structure located at least partially inside a fuel tank of a vehicle, said structure being at least partially submerged in said tank and for use in transporting fuel into said tank, said tubular structure comprising at least one layer (1) having a composition comprising: a. between 39% and 100% by weight, of at least one aliphatic polyamide of formula W/Z wherein: W is an aliphatic repeating unit obtained from the polycondensation of at least one C.sub.6-C.sub.18 lactam, or at least one C.sub.6-C.sub.18 aminocarboxylic acid, or is an aliphatic repeating unit XY having an average number of carbon atoms per denoted nitrogen atom ranging from 6 to 18, obtained from the polycondensation of: at least one C.sub.6-C.sub.18 diamine X, said diamine being selected from a linear or branched aliphatic diamine or a mixture thereof, and at least one C.sub.6-C.sub.18 aliphatic dicarboxylic acid Y; and Z is at least one optional polyamide repeating unit, Z being present at up to 30% by weight relative to the total weight W/Z, b. between 0% and 4% by weight of at least one plasticizer, c. between 0% and 20% of at least one impact modifier, d. between 0% and 37% by weight of at least one additive, the sum of a.+b.+c.+d. being equal to 100%, wherein the partially annulated flexible tubular structure excludes fuel transport structures running from the tank to a motor of the vehicle or in the motor of the vehicle, wherein said structure comprises at least one second layer (2) that is conductive or non-conductive, said layer (1) being located below said layer (2).

2. The tubular structure according to claim 1, wherein the layer (1) is devoid of plasticizer.

3. The tubular structure according to claim 1, wherein said structure is annulated over at least 10% of its length.

4. The tubular structure according to claim 1, wherein at least 90% of the length of said structure is inside the tank.

5. The tubular structure according to claim 1, wherein at least 30% of the length of said structure is submerged in the fuel tank.

6. The tubular structure according to claim 1, wherein said structure comprises at least one second layer (2) that is conductive.

7. The tubular structure according to claim 1, wherein said second layer (2) comprises at least one aliphatic polyamide or fluorinated materials selected from the group consisting of polyvinylidene fluoride (PVDF), functionalized fluorinated materials, functionalized ethylene-tetrafluoroethylene (ETFE) copolymer, functionalized ethylene-tetrafluoroethylene-hexafluoropropylene (EFEP) copolymer, and tetrafluoroethylene-perfluoro (alkylvinylether)-chlorotrifluoroethylene (CPT) copolymer.

8. The tubular structure according to claim 1, wherein said structure is devoid of a barrier layer, said second layer (2) comprising at least one aliphatic polyamide.

9. The tubular structure according to claim 1 wherein said tubular structure passes an extractable test, said test consisting of: filling said tubular structure with FAM-B alcohol-based gasoline, heating the gasoline filled tubular structure at 60° C. for 96 hours, emptying the gasoline from the tubular structure by filtering the gasoline into a beaker, allowing the gasoline filtrate from the beaker to evaporate at ambient temperature, and weighing the gasoline filtrate residue, the proportion of which must be less than or equal to approximately 10 g/m.sup.2 of internal tube surface for the tubular structure to pass the extractable test.

10. The tubular structure according to claim 1, wherein said at least one aliphatic polyamide of constituent a. comprises at least one polyamide denoted C obtained from the polycondensation of at least one C.sub.6-C.sub.18 lactam, or of at least one C.sub.6-C.sub.18 aminocarboxylic acid, and having an average number of carbon atoms per nitrogen atom denoted C.sub.C ranging from 9 to 18.

11. The tubular structure according to claim 10, wherein said at least one aliphatic polyamide of constituent a. further comprises another polyamide selected from the group consisting of: at least one polyamide denoted A having an average number of carbon atoms per nitrogen atom denoted C.sub.A ranging from 4 to 8.5; at least one polyamide denoted B having a melting temperature higher than or equal to 180° C. and an average number of carbon atoms per nitrogen atom denoted C.sub.B ranging from 7 to 10; and a mixture thereof, the weighted average mass of the melting enthalpies of the polyamides A, B and C being higher than 25 J/g (DSC), the average number of carbon atoms per nitrogen atom of the polyamides A, B and C further satisfying the following strict inequation: C.sub.A<C.sub.B<C.sub.C.

12. The tubular structure according to claim 11, wherein the composition comprises between 34 and 84% by weight of aliphatic polyamide C relative to the total weight of the polyamides present within said composition.

13. The tubular structure according to claim 11, wherein polyamide A is selected from the group of PA 6, PA 46, and PA 66; wherein polyamide B is selected from the group of PA 610 and PA 612; and wherein polyamide C is selected from the group of PA 11 and PA 12.

14. The tubular structure according to claim 1, wherein the at least one aliphatic polyamide of formula W/Z comprises at least one aliphatic repeating unit XY, which includes either a polyamide denoted B′ having a melting temperature higher than or equal to 180° C., and an average number of carbon atoms per nitrogen atom denoted C.sub.B′ ranging from 7 to 10, or a polyamide denoted C′ having an average number of carbon atoms per nitrogen atom denoted C.sub.C′ ranging from 9 to 18.

15. The tubular structure according to claim 14, wherein the at least one aliphatic polyamide of formula W/Z further comprises another polyamide selected from the group of: at least one polyamide denoted A having an average number of carbon atoms per nitrogen atom denoted C.sub.A ranging from 4 to 8.5; at least one polyamide denoted B″ having a melting temperature higher than or equal to 180° C. and an average number of carbon atoms per nitrogen atom denoted C.sub.B ranging from 7 to 10 when said aliphatic polyamide comprises polyamide C′; at least one polyamide denoted C″ having an average number of carbon atoms per nitrogen atom denoted C.sub.C″ ranging from 9 to 18, when said aliphatic polyamide comprises polyamide B′; and a mixture thereof, the weighted average mass of the melting enthalpies of the polyamides A, B′, B″, C′ and C″ being higher than 25 J/g (DSC), the average number of carbon atoms per nitrogen atom in polyamides A, B′, B″, C′ and C″ further satisfying the following strict inequation: C.sub.A<C.sub.B″ or C.sub.B″<C.sub.C or C.sub.C″.

16. The tubular structure according to claim 15, wherein (i) polyamide A is selected from the group of PA 6, PA 46, and PA 66; polyamide B′ is selected from the group of PA 610 and PA 612; and polyamide C″ is selected from the group of PA 11, PA 12, PA 1012, PA 618 and PA 1010; or (ii) polyamide A is selected from the group of PA 6, PA 46 and PA 66; polyamide B″ is selected from the group of PA 610 and PA 612; and polyamide C′ is selected from the group of PA 1012, PA 618 and PA 1010.

17. The tubular structure according to claim 14, wherein the composition comprises between 34 and 84% by weight of aliphatic polyamide B′ or aliphatic polyamide C′ relative to the total weight of the polyamides present within said composition.

18. The tubular structure according to claim 1, wherein the additives d. are selected from the group consisting of carbon black, graphite, graphene, carbon fibers, carbon nanotubes, antioxidants, heat stabilizers, UV absorbers, light stabilizers, lubricants, inorganic fillers, fire-proofing agents, nucleating agents, dyes, reinforcing fibers, waxes, and mixtures thereof.

19. The tubular structure according to claim 18, wherein said additives comprise carbon black.

20. The tubular structure according to claim 19, wherein said composition of said layer (1) comprises: a. between 39% and 95% by weight of the at least one aliphatic polyamide, b. between 0% and 4% by weight of the plasticizer, c. between 0% and 20% of the at least one impact modifier, d. between 5% and 32% by weight of carbon black, and between 0 and 5% by weight of at least one additive other than carbon black, graphite, graphene, carbon fibers and carbon nanotubes, the sum a.+b.+c.+d. being equal to 100%.

21. The tubular structure according to claim 19, wherein said composition of said layer (1) comprises: a. between 39% and 85% by weight of the at least one aliphatic polyamide, b. between 0% and 4% by weight of the plasticizer, c. between 10% and 18% of the at least one impact modifier, d. between 5% and 32% by weight of carbon black, and between 0 and 5% by weight of at least one additive other than carbon black, graphite, graphene, carbon fibers and carbon nanotubes, the sum a.+b.+c.+d. being equal to 100%.

22. The tubular structure according to claim 18, wherein said additives comprise carbon nanotubes.

23. The tubular structure according to claim 22, wherein said composition of said layer (1) comprises: a. between 70% and 99.5% by weight of the at least one aliphatic polyamide, b. between 0% and 4% by weight of the plasticizer, c. between 0% and 20% of the at least one impact modifier, d. between 0.5% and 10% by weight of carbon nanotubes, and between 0 and 19% by weight of at least one additive other than carbon black, graphite, graphene, carbon fibers and carbon nanotubes, the sum a.+b.+c.+d. being equal to 100%.

24. The tubular structure according to claim 22, wherein said composition of said layer (1) comprises: a. between 70% and 89.5% by weight of the at least one aliphatic polyamide, b. between 0% and 4% by weight of the plasticizer, c. between 10% and 18% of the at least one impact modifier, d. between 0.5% and 10% by weight of carbon nanotubes, and between 0 and 19% by weight of at least one additive other than carbon black, graphite, graphene, carbon fibers and carbon nanotubes, the sum a.+b.+c.+d. being equal to 100%.

25. The tubular structure according to claim 1, wherein said structure is devoid of any additive selected from the group of carbon black, graphite, graphene, carbon fibers and carbon nanotubes.

26. The tubular structure according to claim 25, wherein the thickness of said layer (1) is at least 600 μm.

27. A method for transporting fuels into a tank, comprising the step of transporting a fuel through a tubular structure according to claim 1.

Description

EXAMPLES

(1) The invention will now be described in more detail with the aid of the following non-limiting examples.

(2) The following structures were prepared by extrusion:

(3) The multi-layer tubes are manufactured by co-extrusion. An industrial McNeil multilayer extrusion line is used, equipped with 5 extruders, connected to a multilayer extrusion head with spiral mandrels.

(4) The screws used are extrusion monoscrews having screw profiles adapted to polyamides. In addition to the 5 extruders and the multilayer extrusion head, the extrusion line comprises: a die-punch assembly, located at the end of the coextrusion head; the internal diameter of the die and the external diameter of the punch are selected according to the structure to be produced and the materials of which it is composed, as well as the dimensions of the tube and the line speed; a vacuum tank with an adjustable vacuum level. In this tank water circulates generally maintained at 20° C., in which a gauge is submerged making it possible to shape the tube to its final dimensions. The diameter of the gauge is adapted to the dimensions of the tube to be produced, typically from 8.5 to 10 mm for a tube with an external diameter of 8 mm and a thickness of 1 mm; a succession of cooling tanks in which water is maintained at around 20° C., allowing the tube to be cooled along the path from the head to the drawing bench; a diameter meter; a drawing bench.

(5) The configuration with 5 extruders is used to produce tubes ranging from 2 layers to 5 layers. In the case of structures whose number of layers is less than 5, several extruders are then fed with the same material.

(6) In the case of structures comprising 6 layers, an additional extruder is connected and a spiral mandrel is added to the existing head, in order to make the inner layer, in contact with the fluid.

(7) Before the tests, in order to ensure the best properties for the tube and good extrusion quality, it is verified that the extruded materials have a residual moisture content before extrusion of less than 0.08%. Otherwise, an additional step of drying the material before the tests, generally in a vacuum dryer, is carried out overnight at 80° C.

(8) The tubes, which satisfy the characteristics disclosed in the present patent application, were removed, after stabilization of the extrusion parameters, the dimensions of the tubes in question no longer changing over time. The diameter is controlled by a laser diameter meter installed at the end of the line.

(9) Generally, the line speed is typically 20 m/min. It generally ranges from 5 to 100 m/min.

(10) The screw speed of the extruders depends on the thickness of the layer and on the diameter of the screw, as is known to those skilled in the art.

(11) In general, the temperatures of the extruders and of the tools (head and connector) must be adjusted so as to be sufficiently higher than the melting temperature of the compositions in question, so that they remain in the molten state, thus preventing them from solidifying and jamming the machine.

(12) The tubular structures were tested on different parameters (Table I).

(13) All the layer thicknesses are expressed in μm.

(14) The amount of extractables, the bursting pressure properties and the flexibility properties were determined.

(15) TABLE-US-00001 Examples and Extractables Bursting Flexibility contrasting examples (3) pressure (1) (2) Contrasting example c1: >50 + +++++ PA12-TL 1000 μm thickness monolayer Contrasting example c2: >40 ++ ++++++ PA11-TL 1000 μm thickness monolayer Contrasting example c3: >40 ++++ ++++ PA610-TL 1000 μm thickness monolayer Contrasting example c4: >40 +++ ++++ PA612-TL 1000 μm thickness monolayer Contrasting example c5 >40 +++ +++++ (multilayer): PA12-TL//PA612-TL//PA12-TL thicknesses: 100//800/100 μm Example 1: <4 ++ +++ PA11-NoPlast 1000 μm thickness monolayer Example 2: <4 ++++ ++ PA610-NoPlast 1000 μm thickness monolayer Example 3: <4 +++ ++ PA612-NoPlast 1000 μm thickness monolayer Example 4: <4 ++++ + PA612-NoPlast-B 1000 μm thickness monolayer Example 5 (multilayer): <5 +++ ++ PA12-NoPlast//PA612-NoPlast thicknesses: 100//900 μm Example 6 (multilayer): <5 +++ +++ PA12-NoPlast//PA612-NoPlast// PA12-NoPlast thicknesses: 100//800//100 μm Example 7 (multilayer): <4 +++ +++ PA11-NoPlast//PA612-NoPlast// PA11-NoPlast thicknesses: 100//800//100 μm Example 8 (multilayer): <4 ++++ +++ PA11-NoPlast//PA610-NoPlast// PA11-NoPlast thicknesses: 100//800//100 μm Example 9 (multilayer): <4 ++++ ++ PA11-NoPlast//PA610-NoPlast// PA11cond-NoPlast thicknesses: 100//800//100 μm Example 10 (multilayer): <2 ++++ ++ EFEPc//PA610-NoPlast//EFEPc thicknesses: 100//800//100 μm Example 11 (multilayer): <2 ++ ++ EFEPc//PA11-NoPlast//EFEPc thicknesses: 100//800//100 μm Example 12 (multilayer): <5 ++++ ++ PA12-NoPlast//Binder- NoPlast//PA6-NoPlast thicknesses: 100//100//800 μm Example 13 (multilayer): <5 +++ +++ PA12-NoPlast//Binder- NoPlast//PA6-NoPlast//Binder- NoPlast//PA12-NoPlast thicknesses: 100//100//600//100//100 μm Example 14 (multilayer): <6 ++++ +++ PA11-TL//PA610-NoPlast thicknesses: 100//900 μm Example 15: <9 ++ +++++ PA11-P 1000 μm thickness monolayer (1) Bursting pressure is the bursting pressure (according to DIN 53758) after at least 96 hours with FAM-B biogas inside, so a value high enough to withstand the pressure is sought. The higher the number of “+”, the better the bursting pressure. (2) Flexibility and flexural modulus (according to ISO 178) on the tube when conditioned at 23° C. in RH50. The lower the modulus, the higher the flexibility, which is favorable for mounting the tube. The higher the number of “+”, the better the flexibility. (3) Extractables. This test consisting of a tube filled with FAM-B alcohol-based gasoline at 60° C. for 96 hours, then emptied and filtered into a beaker which is then allowed to evaporate and the residue of which is weighed, the latter preferably being less than or equal to 6 g/m2 (of internal surface of the tube). The FAM B alcohol-based gasoline is disclosed in standard DIN 51604-1:1982, DIN 51604-2:1984 and DIN 51604-3:1984. In brief, FAM A alcohol-based gasoline is first prepared with a mixture of 50% toluene, 30% isooctane, 15% di-isobutylene and 5% ethanol and then FAM B
Compositions

(16) PA12-TL denotes a polyamide 12-based composition, containing 6% plasticizer, 6% EPR1, and 1.2% organic stabilizers. The melting temperature of this composition is 175° C.

(17) PA11-TL denotes a polyamide 11-based composition, containing 5% plasticizer, 6% impact modifier of the ethylene/ethyl acrylate/anhydride type in a mass ratio of 68.5/30/1.5 (MFI 6 at 190° C. under 2.16 kg), and 1.2% organic stabilizers. The melting temperature of this composition is 185° C.

(18) PA12-NoPlast=PA12-TL without the plasticizer (the latter is replaced by PA12)

(19) PA11-NoPlast=PA11-TL without the plasticizer (the latter is replaced by PA11)

(20) PA610-TL=PA610+12% EPR1 impact modifier+organic stabilizer+10% plasticizer

(21) PA610-NoPlast=PA610-TL without the plasticizer (the latter is replaced by PA610)

(22) PA612-TL=PA612+12% EPR1 impact modifier+organic stabilizer+9% plasticizer

(23) PA612-NoPlast=PA612-TL without the plasticizer (the latter is replaced by PA612)

(24) PA612-NoPlast-B=PA612-TL without the plasticizer or EPR1 (these are replaced by PA612)

(25) PA11cond-noplast=PAU of Mn 15000+9% EPR1+26% Ensaco type carbon black 250 G

(26) PA6-NoPlast=PA6+12% EPR1 impact modifier+organic stabilizer

(27) Binder-NoPlast=Composition based on 48.8% PA612 (as defined elsewhere), 30% PA6 (as defined elsewhere), and 20% EPR1 type impact modifier, and 1.2% organic stabilizers.

(28) EFEPc=Functionalized EFEP and Daikin Neoflon RP5000AS type conductor

(29) PA11-P=denotes a polyamide 11-based composition, containing 1% plasticizer, 6% ethylene/ethyl acrylate/anhydride impact modifier in a mass ratio of 68.5/30/1.5 (MFI 6 at 190° C. under 2.16 kg), and 1.2% organic stabilizers. The melting temperature of this composition is 188° C.
Composition Constituents: PA12: Polyamide 12 of Mn (number-average molecular mass) 35000. The melting temperature is 178° C.; its melting enthalpy is 54 kJ/m2 PAU: Polyamide 11 of Mn (number-average molecular mass) 29000. The melting temperature is 190° C.; its melting enthalpy is 56 kJ/m2 PA610: Polyamide 6.10 of Mn (number-average molecular mass) 30000. The melting temperature is 223° C.; its melting enthalpy is 61 kJ/m2 PA612: Polyamide 6.12 of Mn (number-average molecular mass) 29000. The melting temperature is 218° C.; its melting enthalpy is 67 kJ/m2 PA6: Polyamide 6 of Mn (number-average molecular mass) 28000. The melting temperature is 220° C.; its melting enthalpy is 68 kJ/m2 EPR1: Designating an EPR functionalized by a reactive group with anhydride function (at 0.5-1% by mass), of MFI 9 (at 230° C., below) 10 kg, of Exxellor® VA1801 from Exxon. Organic stabilizer=1.2% organic stabilizers consisting of 0.8% phenol (Lowinox® 44B25 from Great Lakes), 0.2% phosphite (Irgafos® 168 from Ciba, 0.2% UV stabilizer (Tinuvin® 312 from Ciba). Plasticizer=BBSA (benzyl butyl sulfonamide)