Method of making fibrids
AssigneeE. I. Du Pont de Nemours and Company
InventorsArnold Frances, Lee J. Hesler, James E. Van Trump, Rita M. Vasta
Life of this patent
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Abstract
A thickener for liquids is disclosed. The thickener consists of organic polymer fibrid particles with a very small size, a very high aspect ratio, and very low bulk density. The thickener is made by drying newly-coagulated fibrid particles in a way that results in high particulate surface area.
Claims3
A process to make dry fibrids of an organic polymer exhibiting, en masse, a surface area of 50 to 150 m.sup.2 /g, a largest-dimension particle size of 10 to 1000 microns, a largest-to-smallest dimension ratio of 40 to 20,000, and a Critical Concentration of 0.015 to 1% comprising the steps of:
- a) adding, with vigorous agitation, a solution of an organic polymer in a solvent to a liquid which is a nonsolvent for the polymer and is at least partially miscible with the solvent of the solution to cause coagulation of polymer fibrids;
- b) wet milling the coagulated fibrids;
- c) separating the wet milled fibrids from the liquid;
- d) drying the separated fibrids by adding a surfactant to the coagulated fibrids and then evaporating the solvent from the fibrids to yield clumps of fibrids having high surface area;
- and
- e) opening the clumps to obtain a particulate fibrid product.
A process to make dry fibrids of an organic polymer exhibiting, en masse, a surface area of 50 to 150 m.sup.2 /g, a largest-dimension particle size of 10 to 1000 microns, a largest-to-smallest dimension ratio of 40 to 20,000, and a Critical Concentration of 0.15 to 1% comprising the steps of:
- a) adding, with vigorous agitation, a solution of an organic polymer in a solvent to a liquid which is a nonsolvent for the polymer and is at least partially miscible with the solvent of the solution to cause coagulation of polymer fibrids;
- b) wet milling the coagulated fibrids;
- c) separating the wet milled fibrids from the liquid;
- d) drying the separated fibrids by freeze-drying, critical-point drying, or flash drying to yield clumps of fibrids having a high surface area;
- and
- e) opening the clumps to obtain a particulate fibrid product.
Dependencies are inferred from the claim text.