Fibre-forming process and fibres produced by the process
The present invention relates to a process for the preparation of fibers and fibers prepared by the process. The process can provide discontinuous colloidal polymer fibers in a process that employs a low viscosity dispersion medium.
1. A process for the preparation of fibres including the steps of:
(a) injecting a stream of fibre-forming liquid into a dispersion medium at a velocity to provide a stream of fibre-forming liquid upon exposure to the dispersion medium and solidifying the stream of fibre-forming liquid to form a filament in the dispersion medium, wherein the fibre-forming liquid has a viscosity higher than the dispersion medium, and the dispersion medium has a viscosity in the range of from about 1 to 100 centiPoise (cP), and wherein the stream of fibre-forming liquid does not emulsify or break up into discrete droplets when injected into the dispersion medium; and
(b) applying a shear stress to the dispersion medium to fragment the filament under the shear stress and form the fibres.
2. A process according to claim 1 , wherein the dispersion medium has a viscosity in the range of from about 1 to 50 centiPoise (cP).
3. A process according to claim 1 , wherein the dispersion medium has a viscosity in the range of from about 1 to 30 centiPoise (cP).
4. A process according to claim 1 , wherein the dispersion medium has a viscosity in the range of from about 1 to 15 centiPoise (cP).
5. A process according to claim 1 , wherein the ratio of the viscosity of the fibre-forming liquid to the viscosity of the dispersion medium is in the range of from about 2 to 100.
6. A process according to claim 1 , wherein the fibre-forming liquid has a viscosity in the range of from about 3 to 100 centiPoise (cP).
7. A process according to claim 1 , wherein the fibre-forming liquid has a viscosity in the range of from about 3 to 60 centiPoise (cP).
8. A process according to claim 1 , wherein the shear stress has a shear stress rate in the range of from about 100 to about 190,000 cP/sec.
9. A process according to claim 1 , wherein steps (a) and (b) are carried out at a temperature not exceeding 50° C.
10. A process according to claim 1 , wherein steps (a) and (b) are carried out at a temperature not exceeding 30° C.
11. A process according to claim 1 , wherein the fibre-forming liquid is a fibre-forming solution including at least one fibre-forming substance in a solvent.
12. A process according to claim 1 , wherein the fibre-forming liquid includes at least one polymer.
13. A process according to claim 1 , wherein the dispersion medium includes a solvent selected from the group consisting of an alcohol, an ionic liquid, a ketone solvent, water, a cryogenic liquid and dimethyl sulfoxide.
14. A process according to claim 13 , wherein the dispersion medium includes a solvent selected from the group consisting of C 2 to C 4 alcohols.
15. A process according to claim 1 , wherein the fibre-forming liquid contains a polymer in an amount in the range of from about 0.1 to 50% (w/v).
16. A process according to claim 1 , wherein the fibres have a diameter in the range of from about 15 nm to about 5 μm.
17. A process according to claim 16 , wherein the fibres have a length in the range of from about 1 μm to about 3 mm.
18. A process for the preparation of polymer fibres including the steps of:
(a) injecting a stream of polymer solution into a dispersion medium at a velocity to provide a stream of fibre-forming liquid on exposure to the dispersion medium and solidifying the stream of fibre-forming liquid to form a filament in the dispersion medium, wherein the polymer solution has a viscosity higher than the dispersion medium, and the dispersion medium has a viscosity in the range of from about 1 to 100 centiPoise (cP), and wherein the stream of polymer solution does not emulsify or break up into discrete droplets when injected to the dispersion medium; and
(b) applying a shear stress to the dispersion medium to fragment the filament under the shear stress and form the polymer fibres.
19. A process according to claim 18 , wherein the dispersion medium has a viscosity in the range of from about 1 to 50 centiPoise (cP).