Foaming agents for thermoplastic resins and method of preparing same
AssigneeIngenia Polymers Corp.
InventorsArt Tinson, Salvatore D'Uva, Jianzhong Hu, John Lefas
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Abstract
Ultra-fine sodium bicarbonate powder (mean particle size less than 5 microns) is produced by the mixing and reaction under agitation at control temperatures of solutions of ammonium bicarbonate and sodium chloride. Precipitated sodium bicarbonate is separated by filtration as a slurry which is dried to produce ultra-fine sodium bicarbonate. Ultra-fine sodium bicarbonate produced by this method also exhibits a narrow particle size distribution which is advantageous in blowing agents for thermoplastic resins, to produce a foamed resin with small cells of a narrow size distribution.
Claims9
A method of preparing a foaming agent masterbatch for a thermoplastic resin, comprising:
- (a) melt-mixing a selected amount of an ultra-fine sodium bicarbonate powder with a thermoplastic resin and selected amounts of suitable functional additives and minerals;
- and
- (b) cold-pressing the melt into a solidified foaming agent masterbatch composition, wherein said sodium bicarbonate powder is prepared by
- providing an aqueous solution of sodium chloride and an aqueous solution of ammonium bicarbonate;
- mixing the two aqueous solutions in a stirring vessel and stirring at high speed for a period from 20 to 60 seconds at a reaction temperature below 30° C.;
- separating precipitated sodium bicarbonate from the stirred mixture;
- and
- drying the sodium bicarbonate to produce an ultra-fine powder having a particle size of less than 5 microns and a standard deviation in particle size less than the mean particle size.
Dependencies are inferred from the claim text.