Composite pressure vessel with reinforced inner liner and process for the production thereof

1. A composite pressure vessel comprising:

a body comprising an inner liner which comprises a cylindrical portion extending along a longitudinal axis, and which is made of a thermoplastic polymer material; and

an outer thermoset reinforcing structure wrapped around the body and made of a continuous fiber reinforced thermoset matrix composite, comprising reinforcing fibers and a thermoset matrix,

wherein the body further comprises a thermoplastic reinforcement layer made of a continuous fiber reinforced thermoplastic composite, comprising reinforcing fibers and a thermoplastic matrix, which is adhered to the cylindrical portion of the inner liner,

wherein the thermoplastic of the inner liner has a dispersive component, X 2p d =γ 2p d /γ 2p , and the thermoplastic matrix of the thermoplastic reinforcement layer has a dispersive component, x 2c d =γ 2c d /γ 2c , wherein x 2p d =x 2c d ×(1±ε), wherein ε=0.2, or ε=0.15, or ε=0.1, and Wherein γ 2p , γ 2c are the surface energies, and γ 2p d ,γ 2c d , the dispersive surface energies of the thermoplastic of the inner liner and of the thermoplastic matrix of the thermoplastic reinforcement layer, respectively.

2. The composite pressure vessel according to claim 1 , wherein the thermoplastic reinforcement layer comprises a thermoplastic matrix of a polymer family which can be same as or different from the polymer family of the thermoplastic polymer material forming the inner liner, and both polymer families are selected from the group of polyolefins, polyamides, polyesters, polyurethanes, polycarbonates, polyaryletherketone, polyvinyl chloride, wherein the polymer family of the thermoplastic matrix is adhesively compatible with the polymer family of the thermoplastic polymer material forming the inner liner.

3. The composite pressure vessel according to claim 1 , wherein the thermoplastic reinforcement layer is selected among

a filament or tape wound or placed structure with the reinforcing fibers arranged with an angle comprised between 80° and 100° with respect to the longitudinal axis, or

a structure wherein the reinforcing fibers form a braid or a weave.

4. The composite pressure vessel according to claim 1 , wherein the outer thermoset reinforcing structure is selected among

a filament or tape wound or placed structure wherein at least a fraction of the reinforcing fibers is arranged helically with an angle comprised between 5° and 79° with respect to the longitudinal axis and optionally another fraction of the reinforcing fibers is arranged with an angle comprised between 80° and 100° with respect to the longitudinal axis, or

a structure wherein the reinforcing fibers form a braid or a weave.

5. A process for producing the composite pressure vessel according to claim 1 , comprising:

providing the inner liner made of a thermoplastic polymer material and comprising the cylindrical portion extending along a longitudinal axis;

wrapping the thermoplastic reinforcement layer over the cylindrical portion of the inner liner, wherein the thermoplastic reinforcement layer is made of the continuous fiber reinforced thermoplastic composite comprising continuous reinforcement fibers embedded in the thermoplastic matrix;

solidifying the thermoplastic matrix to adhere the continuous fiber reinforced thermoplastic composite to the cylindrical portion of the inner liner, and thus forming the body; and

wrapping the outer thermoset reinforcing structure made of the continuous fiber reinforced thermoset matrix composite over the body to form the composite pressure vessel.

6. The process according to claim 5 , Wherein the thermoplastic reinforcement layer is applied in the form of a preform selected from

a towpreg, wherein unidirectional continuous reinforcing fibers and solid thermoplastic discrete particulate in the form of fibers or powder are in intimate contact, or

a prepreg, wherein unidirectional continuous reinforcing fibers are embedded in a solid continuous thermoplastic matrix,

and wherein the thermoplastic is heated above a melting temperature or a softening temperature to form a heated towpreg or prepreg with molten or softened thermoplastic, prior to winding or placing the heated towpreg prepreg over the cylindrical portion of the inner liner, with application of a pressure in order to drive the impregnation of the fibers by the molten or softened thermoplastic.

7. The process according to claim 5 , wherein the thermoplastic reinforcement layer is applied by

wrapping the inner liner with a fabric obtained by braiding, weaving, or winding towpregs to form a wrapped liner, wherein the towpregs include unidirectional continuous reinforcing fibers intimate contact with solid thermoplastic discrete particulate in the form of fibers or powder,

heating the thus wrapped fabric to melt the thermoplastic discrete particulate of the towpregs,

blowing pressurized gas inside the inner liner with the wrapped liner positioned in a mould cavity to press the fabric and drive an impregnation of the reinforcing fibers by the thus molten thermoplastic, and

cooling the fabric to solidify the thermoplastic matrix.

8. The process according to claim 5 , Wherein thermoplastic reinforcement layer is applied by filament or tape winding or placement by passing a bundle or a tape of continuous reinforcing fibers through a reactive thermoplastic precursor for impregnating the reinforcing fibers and winding or placing the thus impregnated reinforcing fibers about the cylindrical portion of the inner liner and applying the process conditions required for the reactive composition to form the thermoplastic matrix.

9. The process according to claim 5 , wherein the outer thermoset reinforcing structure is applied by filament or tape winding or placement of reinforcing fibers embedded in a reactive thermoset resin over the thermoplastic reinforcement layer.

10. The process according to claim 5 , wherein the outer thermoset reinforcing structure is applied by wrapping the body with a fabric of braided, woven, or filament wound reinforcing fibers and impregnating the fabric with a thermoset resin, and process conditions are maintained to crosslink the thermoset.

11. The process according to claim 5 , wherein the thermoplastic reinforcement layer comprises fibers arranged with an angle comprised between 80° and 100° with respect to the longitudinal axis.

12. The process according to claim 5 , wherein the outer thermoset reinforcing structure comprises at least a fraction of reinforcing fibers arranged helically with an angle comprised between 5° and 79° with respect to the longitudinal axis and optionally another fraction of reinforcing fibers arranged with an angle comprised between 80° and 100° with respect to the longitudinal axis.

13. A composite pressure vessel comprising:

a body comprising an inner liner which comprises a cylindrical portion extending along a longitudinal axis, and which is made of a thermoplastic polymer material; and

an outer thermoset reinforcing structure wrapped around the body and made of a continuous fiber reinforced thermoset matrix composite, comprising reinforcing fibers and thermoset matrix,

wherein the body further comprises a thermoplastic reinforcement layer made of a continuous fiber reinforced thermoplastic composite, comprising reinforcing fibers and a thermoplastic matrix, which is adhered to the cylindrical portion of the inner liner, and

wherein the inner liner further comprises a binding layer sandwiched between the inner liner and the thermoplastic reinforcement layer, for enhancing the adhesion of the thermoplastic reinforcement layer with the inner liner.

14. A process for producing the composite pressure vessel according to claim 13 , comprising:

providing the inner liner made of a thermoplastic polymer material and comprising the cylindrical portion extending along a longitudinal axis;

wrapping the thermoplastic reinforcement layer over the cylindrical portion of the inner liner, wherein the thermoplastic reinforcement layer is made of the continuous fiber reinforced thermoplastic composite comprising continuous reinforcement fibers embedded in the thermoplastic matrix;

solidifying the thermoplastic matrix to adhere the continuous fiber reinforced thermoplastic composite to the cylindrical portion of the inner liner, and thus forming the body; and

wrapping the outer thermoset reinforcing structure made of the continuous fiber reinforced thermoset matrix composite over the body to form the composite pressure vessel.

15. The process according to claim 14 , wherein the thermoplastic reinforcement layer is applied in the form of a preform selected from

a towpreg, wherein unidirectional continuous reinforcing fibers and solid thermoplastic discrete particulate in the form of fibers or powder are in intimate contact, or

a prepreg, wherein unidirectional continuous reinforcing fibers are embedded in a solid continuous thermoplastic matrix,

and wherein the thermoplastic is heated above a melting temperature or a softening temperature to form a heated towpreg or prepreg with molten or softened thermoplastic, prior to winding or placing the heated towpreg or prepreg over the cylindrical portion of the inner liner, with application of a pressure in order to drive the impregnation of the fibers by the molten or softened thermoplastic.

16. The process according to claim 14 , wherein the thermoplastic reinforcement layer is applied by

wrapping the inner liner with a fabric obtained by braiding, weaving or winding towpregs to form a wrapped liner, wherein the towpregs include unidirectional continuous reinforcing fibers in intimate contact with solid thermoplastic discrete particulate in the form of fibers or powder,

heating the thus wrapped fabric to melt the thermoplastic discrete particulate of the towpregs,

blowing pressurized gas inside the inner liner with the wrapped liner positioned in a mould cavity to press the fabric and drive an impregnation of the reinforcing fibers by the thus molten thermoplastic, and

cooling the fabric to solidify the thermoplastic matrix.

17. The process according to claim 14 , wherein thermoplastic reinforcement layer is applied by filament or tape winding or placement by passing a bundle or a tape of continuous reinforcing fibers through a reactive thermoplastic precursor for impregnating the reinforcing fibers and winding or placing the thus impregnated reinforcing fibers about the cylindrical portion of the inner liner and applying the process conditions required for the reactive composition to form the thermoplastic matrix.

18. The process according to claim 14 , wherein the outer thermoset reinforcing structure is applied by filament or tape winding or placement of reinforcing fibers embedded in a reactive thermoset resin over the thermoplastic reinforcement layer.

19. The process according to claim 14 , wherein the outer thermoset reinforcing structure is applied by wrapping the body with a fabric of braided, woven, or filament wound reinforcing fibers and impregnating the fabric with a thermoset resin, and process conditions are maintained to crosslink the thermoset.

20. The process according to claim 14 , wherein the thermoplastic reinforcement layer comprises fibers arranged with an angle comprised between 80° and 100° with respect to the longitudinal axis.

21. The process according to claim 14 , wherein the outer thermoset reinforcing structure comprises at least a fraction of reinforcing fibers arranged helically with an angle comprised between 5° and 79° with respect to the longitudinal axis and optionally another fraction of reinforcing fibers arranged with an angle comprised between 80° and 100° with respect to the longitudinal axis.