PLASTIC LINER FOR A COMPOSITE PRESSURE VESSEL

Abstract

It is proposed a plastic liner for the storage of hydrogen, comprising: a first barrier layer (3), a second barrier layer (7) configured to be an inner layer in contact with hydrogen, at least one intermediate layer arranged between the first and the second barrier layers, wherein the second barrier layer (7) has a lower hydrogen permeability than said at least intermediate layer such that the second barrier layer (7) slows down the migration of hydrogen inside said at least one intermediate layer.

Claims

1. A plastic liner for the storage of hydrogen, comprising: a first barrier layer, a second barrier layer configured to be an inner layer in contact with hydrogen, at least one intermediate layer arranged between the first and the second barrier layers, wherein the second barrier layer has a lower hydrogen permeability than said at least intermediate layer such that the second barrier layer slows down the migration of hydrogen inside said at least one intermediate layer.

2. Plastic liner according to claim 1, wherein the second barrier layer has a higher hydrogen permeability than said first barrier layer.

3. Plastic liner according to claim 1, wherein the hydrogen permeability of the first barrier layer is at least 20% lower compared to the hydrogen permeability of the inner layer.

4. Plastic liner according to claim 1, wherein the first barrier layer is made of ethylene/vinyl alcohol copolymer with a lower ethylene content than the ethylene content of the inner layer.

5. Plastic liner according to claim 1, wherein the inner layer is made of materials selected from the following list: polyvinylidenefluoride (PVDF), polyvinyldichloride (PVDC), aromatic nylon, aliphatic nylon, amorphous nylon, polyethylene terephthalate (PET), LCP, propylene glycol alginate (PGA) and ethylene/vinyl alcohol copolymer (EVOH) with a higher ethylene content than the ethylene content of the first barrier layer.

6. Plastic liner according to claim 1, wherein the inner layer contains fillers.

7. Plastic liner according to claim 1, wherein the inner layer contains polar groups.

8. Plastic liner according to claim 1, wherein it comprises at least one layer based on a reinforced thermoplastic composition.

9. Plastic liner according to claim 1, wherein it comprises an inner layer based on PVDF, a first layer of adhesive, an intermediate layer based on HDPE, a second layer of adhesive, a barrier layer based on EVOH, a third layer of adhesive and an outer layer based on HDPE.

10. Plastic liner according to claim 1, wherein it comprises an inner layer based on PVDF, a first layer of adhesive, an intermediate layer based on HDPE, a second layer of adhesive, a barrier layer based on EVOH, a third layer of adhesive, a layer of re grind and an outer layer based on HDPE.

11. Plastic liner according to claim 1, wherein it comprises an inner layer based on PVDF, a layer based on modified plastic, a first layer of adhesive, a barrier layer based on EVOH, a second layer of adhesive and an outer layer based on HDPE.

12. Plastic liner according to claim 1, wherein it comprises an inner layer based on PVDF, a layer of adhesive and an outer layer based on polyamide.

13. A method of producing a plastic liner having a multilayered wall, comprising the steps of: extruding a multilayer parison tube having a first barrier layer, at least one intermediate layer and an inner layer having a lower hydrogen permeability than said at least one intermediate layer; clamping the parison tube into a hollow cavity mould; blowing the parison against the cavity; and removing the molded plastic liner from the mould.

14. A method of producing a plastic liner having a multilayered wall, comprising the steps of. extruding a multilayer parison tube having a first barrier layer and at least one intermediate layer; clamping the parison tube into a hollow cavity mould; blowing the parison against the cavity; removing the molded plastic liner from the mould; and coating the interior wall of the molded plastic liner with an inner layer having a lower hydrogen permeability than said at least one intermediate layer.

15. A composite pressure vessel comprising a plastic liner as claimed in claim 1.

16. A vehicle comprising a plastic liner as claimed in claim 1.

Description

[0054] The present invention is illustrated in a non limitative way by the examples below relying on FIGS. 1 to 4 attached. In these figures, identical layers bear identical reference numbers.

[0055] FIG. 1 is a schematic cross-sectional view of a multilayer structure of a plastic liner according to a first particular embodiment of the present invention. As illustrated in FIG. 1, the plastic liner can comprise an inner layer (7) based on PVDF, a first layer of adhesive (6), an intermediate layer (5) based on HDPE, a second layer of adhesive (4), a barrier layer (3) based on EVOH, a third layer of adhesive (2) and an outer layer (1) based on HDPE.

[0056] A multilayer structure combining PVDF layer and EVOH layer presents the advantage of increasing the barrier effect (i.e. reducing/eliminating risks of gas permeation), while protecting efficiently the liner against the cracking effects due to blistering.

[0057] FIG. 2 is a schematic cross-sectional view of a multilayer structure of a plastic liner according to a second particular embodiment of the present invention. As illustrated in FIG. 2, the plastic liner can comprise an inner layer (7) based on PVDF, a first layer of adhesive (6), an intermediate layer (5) based on HDPE, a second layer of adhesive (4), a barrier layer (3) based on EVOH, a third layer of adhesive (2), a layer of regrind (8) and an outer layer (1) based on HDPE.

[0058] The term regrind is understood to mean a plastic obtained by grinding the scraps obtained at various stages of the manufacture of a hollow body, for example a fuel tank/pipe or a plastic liner according to the present invention, or by grinding such objects at the end of their life time.

[0059] FIG. 3 is a schematic cross-sectional view of a multilayer structure of a plastic liner according to a third particular embodiment of the present invention. As illustrated in FIG. 3, the plastic liner can comprise an inner layer (7) based on PVDF, a tie layer (5), a first layer of adhesive (4), a barrier layer (3) based on EVOH, a second layer of adhesive (2) and an outer layer (1) based on HDPE.

[0060] In a fourth particular embodiment of the present invention (not illustrated), the plastic liner can comprise an inner layer based on PVDF, a layer of adhesive and an outer layer based on polyamide.

[0061] The term polyamide is understood to mean any homopolymer based on an amide unit, any copolymer comprising at least two different amide units and any copolymer comprising at least 50% by weight of units derived from an amide. It does not matter whether the amide units of this definition are obtained by the opening of the ring of a cyclic polyamide or by the polycondensation of a dicarboxylic acid with a diamine. As examples of polyamides that can be used, mention may be made, non-limitingly, of: PPA (polyphthalamide), PA-6, PA-11, PA-12 and n-mXD6 (polyarylamide). PA-6 is generally preferred.

[0062] In a variant of the invention, the inner layer based on PVDF can be replaced by an inner layer based on EVOH.

[0063] FIG. 4 is a schematic cross-sectional view of a multilayer structure of a plastic liner according to a fourth particular embodiment of the present invention.

[0064] As illustrated in FIG. 4, the plastic liner can comprise an inner layer (16) based on HDPE, a first layer of adhesive (15), a barrier layer (14) based on EVOH, a second layer of adhesive (13), a layer of regrind (12) and an outer layer (11) based on a reinforced thermoplastic composition.

[0065] The invention also concerns a composite pressure vessel comprising a plastic liner as described above.

[0066] The invention also concerns a vehicle comprising a plastic liner as described above.

[0067] The plastic layer of the present invention is particularly suited for the storage of hydrogen.

[0068] In another particular embodiment, the plastic liner of the present invention is adopted for the storage of other types of gas, and in particularly for the storage of compressed natural gas.