Cartridge for an aerosol-generating system

1. A cartridge for use in an aerosol-generating system, comprising:

a liquid storage portion, comprising a housing configured to hold a liquid aerosol-forming substrate, the housing having an opening, wherein the liquid storage portion comprises at least two parts in fluid communication with each other,

a first part of the liquid storage portion comprising

a first capillary material, provided in a vicinity of the opening of the housing, and

a second capillary material in fluid contact with the first capillary material and spaced apart from the opening by the first capillary material, and

a second part of the liquid storage portion comprising a container configured to hold the liquid aerosol-forming substrate and to supply the liquid to the second capillary material.

2. The cartridge according to claim 1 , further comprising a fluid permeable heater assembly extending across the opening of the housing.

3. The cartridge according to claim 1 wherein an average pore size or porosity of the first capillary material is less than an average pore size or porosity of the second capillary material.

4. The cartridge according to claim 1 , wherein the first capillary material has a fiber size or pore size of between 0.1 to 50 μm.

5. The cartridge according to claim 1 , wherein the first capillary material has a density of below 2 g/ml.

6. The cartridge according to claim 5 , wherein the second capillary material has a density of below 1 g/ml.

7. The cartridge according to claim 5 , wherein the second capillary material has a density of between 0.1 and 0.3 g/ml.

8. The cartridge according to claim 1 , wherein the second capillary material has a fiber size or pore size of between 1 to 100 μm.

9. The cartridge according to claim 1 , wherein the first capillary material or the second capillary material is compressed in the housing such that an effective pore size of the first capillary material or the second capillary material is reduced.

10. The cartridge according to claim 9 , wherein a compression of the first capillary material or the second capillary material when placed in the housing is such that a pore size or porosity of the first capillary material or the second capillary material continuously reduces towards the heater assembly.

11. The cartridge according to claim 1 , wherein the first capillary material and the second capillary material comprise different regions of a same capillary material element.

12. The cartridge according to claim 1 , wherein the first capillary material and the second capillary material are formed as an integral element from a continuous piece of capillary material, whereby a cross-section at one end of the integral element s increased.

13. The cartridge according to claim 12 , wherein an inner surface of the housing is shaped in a form of a regular cylinder with a circular cross-section and the continuous piece of capillary material is cone-shaped.

14. The cartridge according to claim 12 , wherein the continuous piece of material has a regular cylindrical shape with a circular cross-section, and wherein an inner surface of the housing comprises a tapered portion at an opening end, such that the continuous piece of capillary material is compressed by the tapered portion upon insertion into the housing.

15. An aerosol-generating system comprising a cartridge according to claim 1 .

16. The aerosol-generating system according to claim 15 , further comprising a mouthpiece, wherein the cartridge is inserted into the system in an orientation such that an opening of the cartridge points away from or towards the mouthpiece.

17. The aerosol-generating system according to claim 15 , wherein the system is an electrically operated smoking system.

18. The cartridge according to claim 1 , wherein the first capillary material has a fiber size or pore size of between 0.5 to 10 μm.

19. The cartridge according to claim 1 , wherein the first capillary material has a fiber size or pore size of about 4 μm.

20. The cartridge according to claim 1 , wherein the first capillary material has a density of about 0.5 g/ml.

21. The cartridge according to claim 1 , wherein the second capillary material has a fiber size or pore size of between 15 to 40 μm.

22. The cartridge according to claim 1 , wherein the second capillary material has a fiber size or pore size of about 25 μm.

23. A cartridge for use in an aerosol-generating system, comprising:

a liquid storage portion, comprising a housing configured to hold a liquid aerosol-forming substrate, the liquid storage portion comprising

a heater assembly, and

a capillary material, provided in contact with the heater assembly,

wherein an average porosity or pore size of a region of the capillary material adjacent to the heater assembly is smaller than an average porosity or pore size of a region of the capillary material remote from the heater assembly, and

wherein the liquid storage portion further comprises at least two parts in fluid communication with each other, the first part of the liquid storage portion comprising the capillary material, and the second part of the liquid storage portion comprising a container configured to hold the liquid aerosol-forming substrate and to supply the liquid to a region having a higher porosity or pore size of the capillary material.

24. The cartridge according to claim 23 , wherein a portion of the capillary material in the region of the capillary material adjacent to the heater assembly is compressed to reduce a porosity or pore size of said material.

25. A method of manufacture of a cartridge for use in an aerosol-generating system, comprising:

providing a liquid storage portion comprising a housing with a first part and a second part, the housing having an opening;

placing a first capillary material in the first part of the housing of the liquid storage portion, such that first capillary material is provided in a vicinity of the opening of the housing; and

placing a second capillary material in the first part of the housing of the liquid storage portion, such that the second capillary material is in contact with the first capillary material and is spaced apart from the opening by the first capillary material,

wherein the second part of the liquid storage portion is substantially empty and is configured to hold a liquid aerosol-forming substrate.

26. The method according to claim 25 , wherein a portion of the first capillary material or the second capillary material is compressed during or before insertion into the housing such that a porosity or pore size of the portion of the first capillary material or the second capillary material is reduced.

27. A method of manufacture of a cartridge for use in an aerosol-generating system, comprising:

providing a liquid storage portion comprising a housing;

providing a heater assembly;

placing a capillary material in the housing of the liquid storage portion, such that the capillary material is provided in direct contact with the heater assembly; and

compressing a portion of the capillary material during or before the placing in the housing such that a porosity or pore size of the portion of the capillary material is reduced,

wherein the provided liquid storage portion further comprises at least two parts in fluid communication with each other, the first part of the liquid storage portion comprising the capillary material, and the second part of the liquid storage portion comprising a container configured to hold a liquid aerosol-forming substrate and to supply the liquid to a region having a higher porosity or pore size of the capillary material.