Method for producing PBI films without organic solvents
A novel process for making PBI films starting from gel PBI membranes polymerized and casted in the PPA process wherein acid-imbibed gel PBIs are neutralized in a series of water baths and undergo controlled drying in association with a substrate material, yielding a PBI film without the use of organic solvents.
1. A process for making a PBI film comprising:
forming a gel PBI membrane via a PPA process;
rinsing the gel PBI membrane;
restraining the gel PBI membrane in at least an X-Y plane direction;
drying the rinsed gel PBI membrane; and
wherein no organic solvent is employed throughout the process.
2. The process of claim 1 , wherein the gel PBI membrane is rinsed with a wash.
3. The process of claim 1 , wherein the rinsed gel PBI membrane is applied to at least one substrate.
4. The process of claim 1 , wherein the rinsed gel PBI membrane is applied to a porous substrate.
5. The process of claim 1 , wherein the PBI film is formed via a continuous formation process.
6. The process of claim 1 , wherein the polybenzimidazole of the PBI film comprises one or more of the following repeating units:
or any combination thereof, in which n and m are each independently 1 or greater.
7. The process of claim 1 , wherein the dried PBI membrane is a self-supporting membrane.
8. The process of claim 1 , wherein the dried PBI membrane is a coating.
9. A PBI film formed according to the process of claim 1 comprising:
forming a gel PBI membrane via a PPA process;
rinsing the gel PBI membrane;
restraining the gel PBI membrane in at least an X-Y plane direction;
drying the rinsed gel PBI membrane to form the PBI film; and
wherein no organic solvent is employed throughout the process to form the film and the dried PBI membrane is free of any organic solvent.
10. The film of claim 9 , wherein the film is used as a coating.
11. The film of claim 9 , wherein the film is incorporated in a laminate.
12. The film of claim 9 , wherein the film has a thickness of from 5 to 150 μm.
13. The film of claim 9 , wherein the film has a stress at break of at least 25 MPa.
14. The film of claim 9 , wherein the polybenzimidazole of the PBI film comprises one or more of the following repeating units:
or any combination thereof, in which n and m are each independently 1 or greater.
15. The film of claim 9 further comprising a PBI polymer which is insoluble in organic solvents.
16. The film of claim 9 further comprising an organic or inorganic acid or base wherein the film is an ionically conducting membrane.
17. The process of claim 6 , wherein n and m are each independently 10 or greater.
18. The process of claim 6 , wherein n and m are each independently 100 or greater.
19. The film of claim 14 , wherein n and m are each independently 10 or greater.
20. The film of claim 14 , wherein n and m are each independently 100 or greater.