MULTILAYER STRUCTURE FOR TRANSPORTING OR STORING HYDROGEN

Abstract

Multilayer structure intended for the transportation, for the distribution and for the storage of hydrogen, including, from the inside toward the outside, at least one leaktightness layer (1) and at least one composite reinforcing layer (2), said innermost composite reinforcing layer being wound around said outermost adjacent leaktightness layer (1), said leaktightness layers having a composition predominantly including: at least one aliphatic polyamide thermoplastic polymer P1i, i=1 to n, n being the number of semicrystalline leaktightness layers, the Tm of which, as measured according to ISO 11357-3: 2013, is greater than 200? C., with the exclusion of a polyether block amide (PEBA), said polyamide thermoplastic polymer being a polyamide exhibiting a mean number of carbon atoms per nitrogen atom of from 7 to 9, up to 30% by weight of impact modifier, up to 1.5% by weight of plasticizer, said composition being devoid of nucleating agent.

Claims

1. A multilayer structure intended for the transportation, for the distribution and for the storage of hydrogen, comprising, from the inside toward the outside, at least one leaktightness layer and at least one composite reinforcing layer, an innermost composite reinforcing layer being wound around an outermost adjacent leaktightness layer, said at least one leaktightness layer consisting of a composition predominantly comprising: at least one aliphatic polyamide thermoplastic polymer P1i, i=1 to n, n being the number of semicrystalline leaktightness layers, the Tm of which, as measured according to ISO 11357-3: 2013, is greater than 200? C., with the exclusion of a polyether block amide (PEBA), said polyamide thermoplastic polymer being a polyamide exhibiting a mean number of carbon atoms per nitrogen atom of from 7 to 9, up to 30% by weight of impact modifier, with respect to the total weight of the composition, up to 1.5% by weight of plasticizer, with respect to the total weight of the composition, said composition being devoid of nucleating agent, it being possible for said at least one polyamide thermoplastic polymer of each leaktightness layer to be identical or different, and at least one of said composite reinforcing layers consisting of a fibrous material in the form of continuous fibers which is impregnated with a composition comprising predominantly at least one polymer P2j, (j=1 to m, m being the number of reinforcing layers), in particular an epoxy or epoxy-based resin or a resin based on polyisocyanates, in particular polyisocyanurates, said structure being devoid of a layer made of polyamide polymer, said layer made of polyamide polymer being the outermost and adjacent to the outermost layer of composite reinforcement.

2. The multilayer structure as claimed in claim 1, wherein the copolymers of ethylene and of ?-olefin are excluded from the impact modifier.

3. The multilayer structure as claimed in claim 1, wherein each reinforcing layer comprises the same type of polymer, in particular an epoxy or epoxy-based resin or a resin based on polyisocyanates.

4. The multilayer structure as claimed in claim 1, wherein the structure exhibits just one leaktightness layer and just one reinforcing layer.

5. The multilayer structure as claimed in claim 1, wherein said polymer P1i is an aliphatic polyamide chosen from PA410, PA412, PA510, PA512, PA610 and PA612.

6. The multilayer structure as claimed in claim 1, wherein said polymer P2j is an epoxy or epoxy-based resin or a resin based on polyisocyanates.

7. The multilayer structure as claimed in claim 5, wherein said multilayer structure consists of just one reinforcing layer and of just one leaktightness layer, in which layers said polymer P1i is an aliphatic polyamide chosen from PA410, PA412, PA510, PA512, PA610 and PA612, and said polymer P2j is an epoxy or epoxy-based resin or a resin based on polyisocyanates.

8. The multilayer structure as claimed in claim 1, wherein the fibrous material of the composite reinforcing layer is chosen from glass fibers, carbon fibers, basalt or basalt-based fibers, or a mixture of these.

9. The multilayer structure as claimed in claim 1, wherein said structure additionally comprises at least one outer layer consisting of a fibrous material made of continuous glass fiber impregnated with a transparent amorphous polymer, said layer being the outermost layer of said multilayer structure.

10. The multilayer structure as claimed in claim 1, wherein said leaktightness layer comprises, from the inside toward the outside: a layer (a) consisting of the composition; optionally a tie layer; a barrier layer to hydrogen; optionally a tie layer; a layer (b) consisting of the composition.

11. A process for the manufacture of a multilayer structure as defined in claim 1, comprising a stage of preparation of the leaktightness layer by extrusion blow molding, by rotational molding, by injection molding or by extrusion.

12. The process for the manufacture of a multilayer structure as claimed in claim 11, comprising a stage of filament winding of the reinforcing layer around the leaktightness layer.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0241] FIG. 1 exhibits the notched Charpy impact at 23? C. and ?40? C. according to ISO 179-1:2010 of five liners in kJ/m.sup.2: from left to right, PA12, PA612, PA610, PA6 and PA66 (for each liner: left-hand histogram: 23? C., and right-hand histogram: ?40? C.).

[0242] FIG. 2 exhibits the permeability to hydrogen at 23? C. in cc.Math.mm/m.sup.2.Math.d.Math.atm of liners from left to right: PA12, PA6, PA610 and PA612.

[0243] FIG. 3 exhibits the permeability to hydrogen at 23? C. in cc.Math.mm/m.sup.2.Math.d.Math.atm of liners of PA610 with different proportions of impact modifier (Lotader? 4700 (50%)+Lotader? AX8900 (25%)+Lucalene? 3110 (25%) mixture): from left to right: PA610 without impact modifier, PA610 with 8% of impact modifier, PA610 with 12% of impact modifier and PA610 with 15% of impact modifier.

[0244] FIG. 4 exhibits the percentage water uptake at 23? C. and 100% relative humidity.

EXAMPLES

[0245] In all the examples, the tanks are obtained by rotational molding of the leaktightness layer (liner) at a temperature suited to the nature of the thermoplastic resin used.

[0246] In the case of the composite reinforcement made of epoxy or epoxy-based resin or a resin based on polyisocyanates, in particular polyisocyanurates, use is subsequently made of a wet filament winding process, which consists in winding fibers around the liner, which fibers are preimpregnated beforehand in a liquid epoxy bath or a liquid epoxy-based bath. The tank is subsequently polymerized in an oven for 2h.

[0247] In all the other cases, use is subsequently made of a fibrous material preimpregnated with the thermoplastic resin (tape). This tape is deposited by filament winding by means of a robot comprising laser heating with a power of 1500 W at the rate of 12 m/min and there is no polymerization stage.

Example 1: Notched Charpy Impact at ?40? C. According to ISO 179-1:2010

[0248] A liner exhibiting a carbon number per nitrogen atom of greater than 9 (PA12), two liners exhibiting a carbon number per nitrogen atom of less than 7 (PA6 and PA66) and two exhibiting a carbon number per nitrogen atom of from 7 to 9 (PA610 and PA612) were prepared by rotational molding as above.

[0249] These five liners were tested in notched Charpy impact at ?40? C. and the results are presented in FIG. 1.

[0250] The impact resistance of the PA610 and PA612 liners is better compared with that of PA6 and PA66.

Example 2

[0251] Permeability of PA12, PA612, PA610 and PA6 Liners without Impact Modifier

[0252] A liner exhibiting a carbon number per nitrogen atom of greater than 9 (PA12), a liner exhibiting a carbon number per nitrogen atom of less than 7 (PA6) and two exhibiting a carbon number per nitrogen atom of from 7 to 9 (PA610 and PA612) were prepared by rotational molding and the permeability to hydrogen at 23? C. was tested.

[0253] This consists in sweeping the upper face of the film with the test gas (hydrogen) and in measuring, by gas chromatography, the flow which diffuses through the film in the lower part, swept by the carrier gas: nitrogen.

[0254] The experimental conditions are presented in table 1:

TABLE-US-00001 TABLE 1 Apparatus Lyssy GPM 500/GC Coupling Detection Chromatographic (TCD) Column Poraplot Q (L = 27.5 m, Dint = 0.530 mm, film thickness = 20?) Carrier gas Nitrogen Diffusing gas Hydrogen U (H.sub.2) Test surface area 50 cm.sup.2 Calibration Absolute by direct injection through a septum Column top pressure 18 psi Oven temperature Isothermal 30? C. Detector temperature 200? C. detector: TCD [] Injector temperature Lyssy injection loop temperature Temperature/Relative 23? C./0% RH humidity

[0255] The results are presented in FIG. 2 and show that the liners made of PA610 and PA612 both exhibit a permeability to hydrogen which is much lower than that of a liner made of PA12.

[0256] FIG. 3 shows the influence of the impact modifier on the permeability to hydrogen of a PA610 liner.

Example 3: Water Uptake

[0257] Test specimens of PA6, PA66, PA610, PA612 and PA12 are immersed in demineralized water at 23? C. Daily (weekends excluded), the samples are removed from the water, wiped, weighed and reintroduced into the water. Once the mass has stabilized (reached a plateau), the value is transferred to the graph. This value corresponds to the maximum mass of water which these products can take up at 23? C.

[0258] FIG. 4 shows that the water uptake of PA612 and PA610 is much lower than that of PA6 and PA66.

[0259] Liners made of PA6, PA610, PA612 and PA12 were covered with a composite casing; the latter is produced by winding T700SC31E carbon fibers (produced by Toray) impregnated with an epoxy resin. The assembly is heated at 110? C. for 5 h to ensure the curing of the epoxy resin. The tanks are subsequently cut up and analyzed. The PA6 liner exhibits bubbles on the outer face (face in contact with the composite structure). The liners made of PA610, PA612 and PA12 do not exhibit any defect.

Example 4

[0260] Type IV hydrogen storage tank, composed of a reinforcer made of epoxy (Tg 120? C.)/T700SC31E carbon fibers (produced by Toray) composite and of a leaktightness layer made of PA612.

[0261] Pressure cycle tests at ?40? C. are carried out on the tanks. The pressure is applied via glycol or a silicone oil, cycles between 20 and 875 bar are applied according to Regulation (EC) No. 79/2009, until 100 cycles or breakage of the tank (deviation with respect to Regulation EC79, which requires 45 000 cycles) have been reached.

[0262] Subsequent to these cycles, the tank is emptied and a hydrogen pressurization test is carried out on the immersed tank. No leakage is observed. Observation of the interior of the tank did not make it possible to identify cracking.

Example 5 (Counterexample)

[0263] Type IV hydrogen storage tank, composed of a reinforcer made of epoxy (Tg 120? C.)/T700SC31E carbon fibers (produced by Toray) composite and of a leaktightness layer made of PA12.

[0264] The same test is carried out with the same result: absence of cracking

[0265] Example 6: Type IV hydrogen storage tank, composed of a reinforcer made of epoxy (Tg 120? C.)/T700SC31E carbon fibers (produced by Toray) composite and of a leaktightness layer made of PA6.

[0266] The same pressure cycle test is carried out but over only 2 cycles. After 2 cycles, the tank is emptied and a hydrogen pressurization test is carried out on the immersed tank. A stream of bubbles is observed, a sign of breakage of the tank. Observation of the interior of the tank confirms this breakage.

[0267] These tests show us that a liner made of PA6 is much less resistant than a liner made of PA612 or PA12.

[0268] The four FIGS. 1 to 4 show that PA610 and PA612 exhibit the best compromise for the impact strength, the permeability and the water uptake compared with PA12, PA6 and PA66.

[0269] A liner made of PA610 or PA612 thus makes it possible to offer a good compromise between mechanical strength and barrier to hydrogen property while providing a reduced water uptake.