Production of a powder of polyvinylchloride or a vinylchloride copolymerizate suitable for producing plastisols
AssigneeA/S Niro Atomizer
InventorsKarsten S. Felsvang, Ove E. Hansen
Life of this patent
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Abstract
An aqueous dispersion of polyvinylchloride or vinylchloride copolymerizate is spray dried in a flow of drying air in a drying tower which contains at least one two-fluid nozzle for atomizing the aqueous dispersion and an injection member for pressurized air for providing the atomized particles with a rotary motion, about the longitudinal axis of the drying tower. A controlled rotary motion is imparted to the mixture of sprayed particles and the drying air. The heat economy and product quality are improved since it is possible to use a high drying air inlet temperature and to obtain an easily grindable powder suitable for producing stable, low viscosity plastisols.
Claims9
A drying tower comprising a tower having a cylindrical part, means at one end thereof for providing a flow of drying air through the tower, at least one two-fluid nozzle for atomizing liquid into the tower by means of pressurised air in which the pressurised air is projected annularly with respect to the liquid, and at least one injector member for injecting air in a direction which, projected onto a plane at right angles to the longitudinal axis of the tower, forms at angle with a line through the centre of the tower and the outlet opening of the injector member, thereby providing within said drying tower a controlled rotary motion of the particles produced by the atomization and the flow of drying air.
A process for the production of a powder of polyvinylchloride or a vinylchloride copolymerisate suitable for the production of plastisols comprising
- (a) atomizing an aqueous dispersion of polyvinylchloride or a vinylchloride copolymerisate into a substantially uniform flow of drying air within a drying tower, so that the drying is carried out substantially as a co-current process, said atomizing taking place via at least one two-fluid nozzle in which pressurised air is projected annularly with respect to said aqueous dispersion of polyvinylchloride or vinylchloride copolymerisate,
- (b) providing within said drying tower a controlled rotary motion of particles produced by the atomization and of the drying air about the longitudinal axis of said drying tower by injecting, via at least one injection member, pressurised air in a direction which, projected onto a plane at right angles to the longitudinal axis of the drying tower, forms an angle with a line through the centre of the drying tower and the injector outlet orifice, and
- (c) grinding at least the coarsest fraction of the resulting powder.
Dependencies are inferred from the claim text.