METHOD FOR PREPARING A HYDROGEN TANK COMPRISING A SEALING LAYER AND A BASE

Abstract

Method for preparing a hydrogen tank including at least one sealing layer of a composition including at least one polyamide P1, and at least one base in order to provide the tank with at least one opening, wherein the method includes: providing of at least one base, the at least one base being covered by at least one layer of a composition including at least one adhesion primer; preparing the at least one sealing layer; fastening the at least one base to the at least one sealing layer.

Claims

1. A method for preparing a hydrogen tank comprising at least one sealing layer consisting of a composition comprising at least one polyamide P1, and at least one base to provide at least one opening in said tank, wherein said method comprises: providing at least one base, said at least one base being covered by at least one layer consisting of a composition comprising at least one adhesion primer, preparing said at least one sealing layer, fastening said at least one base to said at least one sealing layer.

2. The method according to claim 1, wherein said at least one base is metal.

3. The method according to claim 2, wherein said at least one base is degreased and/or stripped/shot-peened before being covered by said at least one layer consisting of a composition comprising at least one adhesion primer.

4. The method according to claim 1, wherein said adhesion primer is in liquid or solid form.

5. The method according to claim 1, wherein said adhesion primer is selected from an aromatic or aliphatic polyurethane, an epoxide, a mixture of an aromatic or aliphatic polyurethane and epoxide, and a mixture of a polyamide P2 and epoxide.

6. The method according to claim 5, wherein said at least one adhesion primer is an epoxide or a mixture of polyester and epoxide.

7. The method according to claim 6, wherein said at least one base is metal and covered by at least one layer consisting of a composition comprising at least one adhesion primer consisting of an epoxide is then covered by a layer consisting of a composition comprising at least one polyamide P2 in powder form.

8. The method according to claim 7, wherein the layer consisting of a composition comprising at least one polyamide P2 has a thickness of from 50 μm to 1500 μm.

9. The method according to claim 5, wherein said composition comprises an adhesion primer consisting of a mixture of at least one epoxide and at least one polyamide P2 and the thickness of the layer is from 1 to 200 μm.

10. The method according to claim 7, wherein said at least one polyamide P2 is a long chain polyamide selected from PA 1010, PA11, PA12, PA1012, PA1212, a mixture thereof or a copolyamide thereof.

11. The method according to claim 6, wherein it comprises a step of crosslinking said epoxide.

12. The method according to claim 11, wherein said adhesion primer consists of an epoxide, said sealing layer being prepared by rotational molding in a mold, and the crosslinking step is carried out during the rotational molding after prior introduction of said base into the rotational molding mold before the preparation of said sealing layer.

13. The method according to claim 11, wherein said adhesion primer consists of an epoxide, said sealing layer being prepared by rotational molding in a mold, the crosslinking step being carried out during a pre-firing step before introduction of said base into the rotational molding mold before preparation of said sealing layer.

14. The method according to claim 11, wherein said adhesion primer consists of an epoxide, said sealing layer being previously prepared by injection, thermoforming or extrusion blow molding, said crosslinking being carried out during a pre-firing step before the fastening of said at least one base to said at least one previously prepared sealing layer.

15. The method according to claim 11, wherein said adhesion primer consists of an epoxide, said sealing layer being prepared by injection, thermoforming or extrusion, said crosslinking being carried out during a pre-firing step before the fastening of said at least one base to said at least one sealing layer.

16. The method according to claim 11, wherein said adhesion primer consists of an epoxide, the crosslinking step being carried out during a pre-firing step and said base heated and covered by crosslinked epoxide is then dipped into a fluidized bed of polyamide P2 or a polyamide powder P2 is sprayed before the fastening of said at least one base to said at least one previously prepared sealing layer.

17. The method according to claim 11, wherein said at least one metal base is covered by at least one layer consisting of a composition comprising at least one adhesion primer consisting of an epoxide covered with a layer consisting of a composition comprising at least one polyamide P2 in powder form, said base being previously covered with an epoxide then said polyamide P2 in powder form being applied to said base, said base being then passed into a furnace in order to crosslink said epoxide and enable the melting of the polyamide P2.

18. The method according to claim 11, wherein said at least one metal base is covered by at least one layer consisting of a composition comprising at least one adhesion primer consisting of a mixture of a polyamide P2 and an epoxide, said base then being passed into a furnace in order to crosslink said epoxide and enable the melting of polyamide P2.

19. The method according to claim 16, wherein said sealing layer is prepared beforehand by rotational molding, by injection, thermoforming or extrusion blow molding, said crosslinking being carried out during a pre-firing step before the fastening of said at least one base to said at least one previously prepared sealing layer.

20. The method according to claim 12, wherein the tank comprises at least one composite reinforcement layer consisting of a fibrous material in the form of continuous fibers impregnated by a composition predominantly comprising at least one thermoset polymer P4, especially epoxide-based.

21. The method according to claim 12, wherein the tank comprises at least one composite reinforcement layer consisting of a fibrous material in the form of continuous fibers impregnated by a composition predominantly comprising at least one polyamide P3.

22. The method according to claim 20, wherein said at least one composite reinforcement layer is wound around the layer.

23. The method according to claim 20, wherein polyamide P3j is an aliphatic polyamide.

24. The method according to claim 1, wherein said at least one polyamide P1 is a semi-aromatic copolyamide comprising at least two distinct units A and XY of formula A/XY, wherein: A is a repeating unit obtained by polycondensation: of at least one C9 to C18, amino acid, or of at least one C9 to C18, lactam, or of at least one C4-C36 Ca diamine, with at least one C4-C36 Cb dicarboxylic acid, XY is a repeating unit obtained from the polycondensation of at least one C9 to C18 linear aliphatic diamine (X) and of at least one aromatic dicarboxylic acid (Y).

25. The method according to claim 1, wherein said at least one polyamide P1 is a short chain aliphatic polyamide having an average number of carbon atoms per nitrogen atom of from 4 to 8.5, or a long chain polyamide having an average number of carbon atoms per nitrogen atom greater than 8.5.

26. The method according to claim 25, wherein the short chain aliphatic polyamide is polyamide 6 and the long chain aliphatic polyamide is selected from polyamide 11, polyamide 12, polyamide 1010, polyamide 1012, polyamide 1212, or a mixture thereof or a copolyamide thereof.

27. The method according to claim 25, wherein said at least one aliphatic polyamide P1 is selected from PA6, PA11 and PA12.

Description

DESCRIPTION OF THE FIGURES

[0215] FIG. 1 shows an example of a hydrogen tank (1) comprising a sealing layer (2), a base (3), a composite reinforcement layer (4) and an opening (5) and the joining (6) of the base (3) with the sealing layer (2).

EXAMPLES

Example 1: Preparation of a Tank Comprising a Sealing Layer (2) Made from PA 11, a Metal Base (3) Covered with Epoxy Primer and a Composite Reinforcement Layer Made from Carbon Fibers with an Epoxy Matrix

[0216] The base is shot-peened at the contact zone with the sealing layer. 2 hours after this step, a primer layer, supplied by Arkema under the name Primgreen® LAT 12035, is applied by spraying in such a way a homogeneous white color to the eye. It is then left to dry in a ventilated location until the white color disappears.

[0217] This base is then introduced into a furnace at 270° C. for 30 minutes. Upon exiting the furnace, a brown color is visible at the application zones of the primer; which color is defined in the procedures supplied by Arkema. Polyamide powder, supplied by Arkema, under the reference Rilsan® PA11 T nat BHV2, is sprayed onto the hot base in order to achieve a thickness of approximately 400 μm. The base is then left to cool, until a temperature of less than 50° C. is reached.

[0218] The base thus coated is then introduced into a rotational molding mold. Powder of PA 11, sold by Arkema under the name Roto 11 natural, is introduced into the mold. The temperature inside the mold is monitored during the rotational molding step. This mold is heated, whilst being rotated, until the temperature inside the mold reaches 220° C. Heating is then stopped, and the mold cooled.

[0219] The method is stopped when a temperature of 70° C. is reached. The heating/cooling cycle lasts 1 hour.

[0220] The sealing layer is then covered by a 2 cm thick composite containing carbon fibers and an epoxy resin. The fibers are unwound from the spools on which they are supplied and wound around the sealing layer. Between the spools and the tank being constructed, they pass through a liquid epoxy bath to be impregnated with this resin. Once the 2 cm thickness is achieved in any part of the tank (except at the openings), the tank is introduced into an autoclave at 80° C. for 8 h.

Comparative Example 2: Preparation of a Tank Comprising a PA 11 Sealing Layer (2), a Metal Base (3) without Epoxide and a Composite Reinforcement Layer Made from Carbon Fibers with an Epoxy Matrix

[0221] The same test as in example 1 is carried out, with the exception of the following steps which are not carried out: [0222] After shot-peening, no primer is applied [0223] The drying step specific to the primer is not carried out

[0224] The method previously disclosed resumes with the heating of the base in a furnace, and spraying of the PA11 powder.

[0225] Adhesion results with the two different bases.

[0226] Following these 2 tank preparations, the quality of the adhesion on the base is assessed. To simulate aging, the tank is cut around the base, leaving 2 cm around the entire base. The largest coated surface of the base (internal face of the tank) is then marked; a diagonal cross is carved therein, by cutting the layer of PA11 until the metal is reached. The diagonal cross is located in the vicinity of the center of this largest surface. The part is then introduced into a climate chamber to perform a salt fog test for 2000 h.

[0227] At the end of the test, the adhesion quality is assessed by removing the surface of PA 11 no longer adhering to the base (by applying a knife blade under the surface, in the center of the cross, the layer of PA11 must be able to be lifted with just the force required to deform the layer of PA 11). The maximum delamination from the center of the cross is measured. [0228] For the base prepared with primer (example 1), the greatest delamination distance reaches 8 mm. [0229] For the base prepared without primer (example 2), the greatest delamination distance reaches the edge of the base, of the order of 4 cm