Method of making supercritical fluid molecular spray films, powder and fibers
US4734227A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 12, 1986 |
| Grant date | Mar 29, 1988 |
| Priority date | — |
| Expiry date | Mar 12, 2006 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29B2009/125
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a heated nozzle having a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. In another embodiment, the temperature of the solution and nozzle is elevated above the melting point of the solute, which is preferably a polymer, and the solution is maintained at a pressure such that, during expansion, the solute precipitates out of solution within the nozzle in a liquid state. Alternatively, a secondary solvent mutually soluble with the solute and primary solvent and having a higher critical temperature than that of primary solvent is used in a low concentration (<20%) to maintain the solute in a transient liquid state. The solute is discharged in the form of long, thin fibers. The fibers are collected at sufficient distance from the orifice to allow them to solidify in the low pressure/temperature region.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.