Methods for forming stabilized metal salt particles

Abstract

The present invention relates to a process for forming stabilized metal salt particles.

1 . A process comprising
 a. forming a first solution comprising at least one salt precursor;   b. forming a second solution comprising a complex formed from at least one metal agent and at least one dispersing agent in a particle size stabilizing effective amount;   c. adding said second solution to said first solution at a rate sufficient to maintain a clear solution throughout addition and to form a product solution comprising stabilized metal salt particles having a mean particle size of less than about 200 nm;   d. drying said product solution to form an antimicrobial metal salt powder comprising 0.01 to about 10 weight % metal in the antimicrobial metal salt powder.   
   
   
       2 . The process of  claim 1  wherein said second solution has a metal agent concentration of at least about 1500 ppm. 
   
   
       3 . The process of  claim 1  wherein the dispersing agent is present in said second solution in a concentration between about 20 and about 50 w/w %. 
   
   
       4 . The process of  claim 1  wherein said first solution has a salt precursor concentration of at least about 1500 ppm. 
   
   
       5 . The process of  claim 1  wherein said first solution has a salt precursor concentration of at least about 5000 ppm. 
   
   
       6 . The process of  claim 1  wherein said first solution has a salt precursor concentration of about 5000 ppm to about 50,000 ppm. 
   
   
       7 . The process of  claim 1  wherein said mean particle size is less than about 100 nm. 
   
   
       8 . The process of  claim 1  wherein said mean particle size is less than about 50 nm. 
   
   
       9 . The process of  claim 1  wherein said first and second solutions are aqueous solutions. 
   
   
       10 . The process of  claim 1  wherein said product solution has a viscosity of less than about 50 cps. 
   
   
       11 . The process of  claim 1  wherein said first solution is stirred as said second solution is added. 
   
   
       12 . The process of  claim 9  wherein said solutions are maintained at a pressure between about ambient and about 40 mbar during said adding step. 
   
   
       13 . The process of  claim 1  wherein said dispersing agents are independently selected from the group consisting of hydroxyalkylmethylcellulose polymers, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide, starch, pectin, polyacrylamide, gelatin, polyacrylic acid, organoalkoxysilanes 3-aminopropyltriethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, and 3-glycidoxypropyltrimethoxysilane, boric acid ester of glycerin and mixtures thereof. 
   
   
       14 . The process of  claim 1  wherein at least one of said first and second solution comprises at least one solvent and said powder comprises less than about 10 wt % of said solvent. 
   
   
       15 . The process of  claim 14  wherein said powder comprises less than about 5% of said solvent. 
   
   
       16 . The process of  claim 14  wherein said solvent comprises water. 
   
   
       17 . The process of  claim 14  wherein said metal agent comprises at least one silver salt which is soluble in said at least one solvent. 
   
   
       18 . The process of  claim 13  wherein said dispersing agent comprises polyvinyl pyrrolidone. 
   
   
       19 . The process of  claim 18  wherein said polyvinyl pyrrolidone and metal agent are present in said second solution in a molar ratio of at least about 1.5. 
   
   
       20 . The process of  claim 1  wherein said metal salt has a K sp  of less than about 2×10 −10  in pure water at 25° C. 
   
   
       21 . The process of  claim 1  wherein said metal salt has a K sp  of not more than about 2.0×10 −17  moles/L. 
   
   
       22 . The process of  claim 1  wherein said second solution has a metal agent concentration of at least about 5000 ppm. 
   
   
       23 . The process of  claim 1  wherein said first solution has a metal agent concentration of about 5000 ppm to about 50,000 ppm. 
   
   
       24 . A process comprising
 a. forming a first solution comprising NaI;   b. forming a second solution comprising a complex formed from AgNO 3  and polyvinyl pyrrolidone in a particle size stabilizing effective amount;   c. adding said second solution to said first solution at a rate sufficient to maintain a clear solution throughout addition and to form a product solution comprising stabilized AgI particles having a mean particle size of less than about 200 nm;   d. drying said product solution to form an antimicrobial AgI powder comprising 0.01 to about 10 weight % Ag in the antimicrobial AgI powder.