Polymerization, compatibilized blending, and particle size control of powder coatings in a supercritical fluid
US6340722B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 4, 1998 |
| Grant date | Jan 22, 2002 |
| Priority date | — |
| Expiry date | Sep 4, 2018 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S525/934
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The current process for producing powder coatings can be replaced with a process utilizing supercritical fluids including polymer polymerization, compatibilized blending of powder coating ingredients, and particle size control and classification of the powder coating. Traditionally, powder coating resins are polymerized in solvent based system. Next, the resin is blended with additives in a twin screw extruder at high temperatures. The material is then ground and separated by particle size to form the finished powder coating. This invention replaces the previous process by performing all operations in a supercritical fluid, preferably, carbon dioxide. Polymerization is conducted at any pressure above critical pressure and temperature above critical temperature up to 190° C. Solubility of the polymer in the supercritical fluid allows for control and narrow distribution of the molecular weight and a polydispersity of about 2 or less. Compatibilized blending is effected by a chemical or a physical technique to encapsulate the powder coating additives in the polymer. Particle size control is effected by stepwise controlled depressurization of the mixing chamber or through controlle…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.