Cold water-insoluble polyvinyl alcohol pouch for the controlled release of active ingredients
AssigneeAirwick Industries, Inc.
InventorPing I. Lee
Life of this patent
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Abstract
A pouch for the controlled release of active ingredients into an aqueous medium comprising liquid or solid active ingredients enclosed in a sealed envelope of cold water-insoluble polyvinyl alcohol.
Claims12
A sealed pouch for the controlled release of chlorinating agent into an aqueous medium having a maximum of 60.degree. C. consisting of an envelope of cold water insoluble polyvinyl alcohol in film form, said polyvinyl alcohol being at least about 99% hydrolyzed and having a minimum degree of swelling in water of about 120%, and enclosed therein an effective amount of a chlorinating agent having at least a minimum solubility in water, the pH of said aqueous solution of chlorinating agent being in the range of from 2.5-10.0;
- said sealed pouch having a maximum ratio of weight of active ingredient to pouch volume of about 50 lb/ft.sup.3.
A method for the controlled release of chlorinating agent into an aqueous medium having a maximum temperature of 60.degree. C. consisting of the steps of (1) preparing a sealed pouch of cold water-insoluble polyvinyl alcohol in film form, said polyvinyl alcohol being at least about 99% hydrolyzed and having a minimum degree of swelling in water of about 120%, and enclosed therein an effective amount of a chlorinating agent having at least a minimum solubility in water;
- said sealed pouch having a maximum ratio of weight of active ingredient to pouch volume of about 50 lb/ft.sup.3 ;
- (2) introducing said sealed pouch into said aqueous medium;
- (3) swelling said polyvinyl alcohol film;
- (4) introducing the aqueous medium into said pouch to dissolve said chlorinating agent;
- said aqueous solution of chlorinating agent having a pH in the range of 2.5-10.0;
- and (5) allowing said chlorinating agent to diffuse through said swollen film and be released into said aqueous medium;
- said release being capable substantially ceasing upon removal of the pouch from said aqueous medium and the drying thereof and being reinitiated upon renewed contact of the pouch with said aqueous medium.
Dependencies are inferred from the claim text.