Method of encapsulating particulate materials

Abstract

A method of encapsulating particulate materials that enables the particulate materials to be used in end use applications where they currently are not useful. The method uses specific sol gel technology to encapsulate solid particles. In addition, the method can be used to multiple coat a coated particle.

1 . A method of encapsulating particulate materials, the method comprising:
 a. providing acidified water at least sufficient for hydrolyzing a predetermined amount of alkoxysilane;   b. dispersing at least one type of particulate material in the acidified water;   c. slowly adding a predetermined amount of alkoxysilane having the general formula:
   R x Si(OR′) 4-x  
 
    wherein R is selected from the group consisting essentially of alkyl groups, substituted alkyl groups, aryl groups, substituted aryl groups, vinyl, allyl, and hydrogen, wherein the substituents are selected from the group consisting of fluorine, amino, hydroxy, and combinations thereof, and wherein R′ is selected from hydrogen and alkyl groups of 1 to 4 carbon atoms;   d. allowing sufficient time for the alkoxysilane to hydrolyze and build a predetermined particle size.   
     
     
         2 . The method as claimed in  claim 1  wherein, in addition, there is a step e. in which the product of d. is neutralized with base. 
     
     
         3 . The method as claimed in  claim 1  wherein, in addition, the water is removed from the dispersion and any solids in the dispersion are dried. 
     
     
         4 . The method as claimed in  claim 2  wherein, in addition, the dry solids are ground to a fine powder. 
     
     
         5 . An encapsulated particulate material prepared by the method of  claim 1 . 
     
     
         6 . A method as claimed in  claim 1  in which an encapsulated material from the method of  claim 1  is further subjected to the method of  claim 1  to provide an additional coating of encapsulation material. 
     
     
         7 . A method as claimed in  claim 5  in which more than two coats are provided for an encapsulated material.