Abstract:
Improved methods and apparatus for particle precipitation and coating using near- or supercritical fluid conditions are described. A fluid dispersion having a continuous phase dispersant and at least one precipitatable substance therein is contacted with a supercritical fluid (SCF) antisolvent so as to generate focused high frequency antisolvent sonic waves, breaking up the dispersion into extremely small droplets; the enhanced mass transfer rates between the droplets and the antisolvent causes precipitation of very small particles on the order of 0.1-10 .mu.m. In coating processes, a turbulent fluidized flow of core particles is created using an SCF antisolvent in an enclosed zone. The core particles are contacted therein at near- or supercritical conditions by a fluid dispersion containing a dispersant together with a precipitatable substance. The antisolvent depletes the dispersant and the substance is precipitated onto the fluidized core particles. In another aspect of the invention, a process for preparing and administering a medicament using only a single container is provided. In such method, a fluid dispersion having a dispersant with the medicament therein is contacted with an antisolvent at near- or supercritical conditions within a use container, so as to directly precipitate small particles of the medicament in the container. The antisolvent is then removed and the use container is sealed with the medicament particles therein. Thereafter, dose(s) of the medicament can be withdrawn from the use container and administered to a patient.
Abstract:
Methods and apparatuses are provided for forming fine particles of a desired substance comprising dissolving said substance in a fluid such as water to form a solution and mixing the solution with a second fluid such as supercritical carbon dioxide which becomes a gas upon rapid pressure release, and with which the first fluid is at least partially immiscible, and releasing the pressure to form an air-borne dispersion or aerosol comprising particles having an average diameter between about 0.1 and about 6.5 .mu.m.
Abstract:
A process for making a fluoropolymer is disclosed. The process comprises solubilizing a fluoromonomer in solvent comprising a carbon dioxide fluid, and then polymerizing the fluoromonomer to produce the fluoropolymer. A preferred solvent for carrying out the process is supercritical carbon dioxide; preferred fluoromonomers for carrying out the process are fluoroacrylate monomers such as 1,1-dihydroperfluorooctyl acrylate. The polymerization step is preferably carried out in the presence of an initiator such as azobisisobutyronitrile.
Abstract:
The present invention is directed to methods and apparatus for effectively proportioning a mixture of compressible and non-compressible fluids, wherein the resulting mixture has an almost constant density. The present invention is particularly useful for admixing supercritical fluids with polymeric coating compositions for various spray applications.
Abstract:
The present invention is directed to methods for spraying water-borne coating compositions having at least about thirty five percent by weight of the solvent fraction by using compressed fluids such as carbon dioxide and ethane, so as to decrease runs, sags and drying time in the application of coatings.
Abstract:
The present invention provides a new and improved method of producing coating materials comprising the steps of providing a first organic material which is solid at room temperature, providing a second organic material which is solid at room temperature and which is substantially different in chemical composition from the first organic material, providing a source of supercritical fluid, providing a first container having a mechanical agitator, providing a second container, introducing the first and second organic materials and the supercritical fluid into the first container and mechanically agitating such materials and the supercritical fluid, and discharging the contents of the first container into the second container so as to collect substantially all of the first and second organic materials in the second vessel, the second container being maintained at a lower pressure than the first container.
Abstract:
Methods are presented by which polymeric compositions, such as coating compositions, can be sprayed with compressed fluids, such as carbon dioxide, nitrous oxide, or ethane, at higher solids levels and with finer atomization to give improved spray application quality with reduced emission of solvent.
Abstract:
A liquid coatings application process and apparatus is provided in which supercritical fluids, such as supercritical carbon dioxide fluid, are used to reduce to application consistency viscous coatings compositions to allow for their application as liquid sprays. The coatings compositions are sprayed by passing the composition under pressure through an orifice into the environment of the substrate.
Abstract:
This invention is directed to improved spraying apparatus for coating substrates with a coating material and supercritical fluid which apparatus is provided with various features, either alone or in combination, to prevent undesirable premature cooling of the coating mixture which might detrimentally affect the final coating on the substrate; to prevent undesirable depressurization of supercritical fluid contained in the coating mixture which remains in the spray gun after spraying has been stopped; and/or to desirably provide the ability to mix the components of the coating mixture directly in the spray gun. Methods for utilizing these features in the spraying apparatus of the present invention are also disclosed.
Abstract:
A liquid coatings application process and apparatus is provided in which supercritical fluids, such as supercritical carbon dioxide fluid, are used to reduce to application consistency viscous coatings compositions to allow for their application as liquid sprays.