Process for the production of a structured film
The present invention relates to a process for the formation of a structured film, a structured film as such, an article comprising the structured film, a device for the continuous formation of such a structured film and a composite comprising the structured film.
1. A process for the formation of a structured porous film comprising:
a) applying a porous film onto an elastic substrate in a stretched state such that a reversible adhesion of the porous film on the stretched substrate occurs,
b) relaxing the substrate with the applied film thereon to obtain a structured porous film, and
c) removing the structured porous film from the substrate.
2. The process according to claim 1 , further comprising applying a backer material to the structured porous film.
3. The process according to claim 1 , wherein the porous film comprises a member selected from fluoropolymer, a polyvinylalcohol, a polyurethane and combinations thereof.
4. The process according to claim 3 , wherein the porous film comprises a member selected from polytetrafluoroethylene (PTFE) a modified PTFE, a fluorothermoplastic, a fluoroelastomer and combinations thereof.
5. The process according to claim 1 , wherein the porous film has a thickness between 0.5 μm and 250 μm.
6. The process according to claim 1 , wherein the substrate comprises a member selected from a polysiloxane, fluorosilicone a rubber and combinations thereof.
7. The process according to claim 1 , wherein the substrate is stretched at a processing ratio of at least 110% in at least one direction.
8. The process according to claim 1 , wherein the elastic substrate is stretched at a processing ratio of at most 1100% in at least one direction.
9. A structured porous film obtained by the process according to claim 1 .
10. The structured film according to claim 9 , wherein structures in the structured film have a height of at least two times the thickness of a non-structured film, and wherein the structure density in at least one direction is at least 1/mm.
11. A structured porous film comprising a porous film reversibly adhered to an elastic substrate, wherein structures in the porous film have a height at least two times the thickness of a non-structured film and the structure density in at least one direction is at least 1/mm.
12. The structured porous film according to claim 11 , wherein the structure density in at least one direction is at least 2/mm.
13. The structured porous film according to claim 12 , wherein the structure height is from 2 μm to 2000 μm.
14. The structured porous film according to claim 13 , wherein the area increase factor of the structured film is at least 1.8.
15. An article comprising a structured porous film according to claim 11 , wherein said elastic substrate is removed.
16. The article according to claim 15 , wherein the article is a vent or a filter.
17. A structured porous film obtained by the process of claim 1 , wherein said structured porous film has applied thereto a backer material to form a composite, and wherein said composite has an asymmetric airflow of at least 30%.
18. A composite comprising a structured film obtained by the process of claim 1 and having an asymmetric airflow of at least 30%.
19. A structured porous film consisting of:
a porous film having structures in the porous film that have a height at least two times the thickness of a non-structured film and the structure density in at least one direction is at least 1/mm,
wherein said porous film has a multi-layered structure.
20. The structured porous film according to claim 19 , wherein the structure density in at least one direction is at least 2/mm.
21. The structured porous film according to claim 20 , wherein the structure height is from 2 μm to 2000 μm.
22. A structured porous film comprising:
a porous film having structures therein that have a height at least two times the thickness of the non-structured film and the structure density in at least one direction is at least 1/mm,
wherein said structures are permanent in said porous film separate from a substrate.
23. The structured porous film according to claim 22 , wherein the structure density in at least one direction is at least 2/m.
24. The structured porous film according to claim 22 , wherein the structure height is from 2 μm to 2000 μm.
25. The structured porous film according to claim 24 , wherein the area increase factor of the structured film is at least 1.8.
26. The structured porous film according to claim 22 , wherein said porous film has a multi-layered structure.
27. The structured porous film according to claim 11 , wherein said porous film has a multi-layered structure.
28. The composite of claim 18 , wherein said composite is in the form of a vent or filter.