Aqueous microcapsule slurry

Abstract

An aqueous slurry composition containing microcapsules dispersed in an aqueous medium. The microcapsules contain an ionic acrylate copolymer shell encapsulating an oily medium. Upon drying, the microcapsules release the oily medium. The slurry is useful in delivering a variety of water-insoluble substances via an aqueous medium including cosmetic or agricultural agents.

What is claimed is: 
     
         1 . An aqueous slurry composition, comprising an aqueous medium having dispersed therein oily medium-containing microcapsules, wherein the oily medium-containing microcapsules comprise an ionic acrylate copolymer shell encapsulating said oily medium. 
     
     
         2 . The composition according to  claim 1 , wherein said ionic acrylate copolymer was made from only water-soluble monomers. 
     
     
         3 . The composition according to  claim 2 , wherein said ionic acrylate copolymer is comprised of a mono-functional acrylate monomer having an ionic group and a multi-functional acrylate monomer. 
     
     
         4 . The composition according to  claim 3 , wherein ionic acrylate copolymer is an anionic copolymer and said mono-functional acrylate monomer contains an anionic group. 
     
     
         5 . The composition according to  claim 4 , wherein said anionic group is a carboxylic acid. 
     
     
         6 . The composition according to  claim 3 , wherein ionic acrylate copolymer is a cationic copolymer and said mono-functional acrylate monomer contains a cationic group. 
     
     
         7 . The composition according to  claim 6 , wherein said cationic group is an ammonium group. 
     
     
         8 . The composition according to  claim 3 , wherein said multifunctional acrylate is an ethoxylated trimethylolpropane triacrylate. 
     
     
         9 . The composition according to  claim 3 , wherein the weight ratio of mono-functional acrylate to multi-functional acrylate is within the range of 30:70 to 70:30, respectively. 
     
     
         10 . The composition according to  claim 1 , wherein said ionic acrylate copolymer shell comprises, on average, 5 to 25% by weight of the microcapsule. 
     
     
         11 . The composition according to  claim 1 , wherein said oily medium comprises a pesticide, herbicide, and/or plant fertilizer. 
     
     
         12 . The composition according to  claim 1 , wherein said oily medium comprises a fragrance, a UV-absorber, and/or a skin moisturizer. 
     
     
         13 . The composition according to  claim 1 , wherein said microcapsules release less than 10% of said oily medium over four weeks of storage but release all of the oily medium once the aqueous medium is removed. 
     
     
         14 . The composition according to  claim 13 , wherein said microcapsules release 80-100% of said oily medium within 6 hours after aqueous medium removal. 
     
     
         15 . The composition according to  claim 14 , wherein said microcapsules release less than 5% of said oily medium over four weeks of storage. 
     
     
         16 . A process of making an aqueous slurry composition, which comprises:
 (a) combining an oily medium, which contains an oil-soluble polymerization initiator, with an aqueous medium, which contains a water-soluble polymerization initiator, a water-soluble mono-functional acrylate monomer having an ionic group, a water-soluble multi-functional acrylate monomer, and/or water-soluble polymerizates thereof, to form an emulsion wherein the oily medium is the dispersed phase in the form of droplets and the aqueous medium is the continuous phase; and   (b) subjecting said emulsion to sufficient temperature and duration to polymerize and/or deposit an ionic acrylate copolymer shell around the droplets to thereby encapsulate said oily medium and form said aqueous slurry.   
     
     
         17 . The process according to  claim 16 , which further comprises combining said water-soluble polymerization initiator, said water-soluble mono-functional acrylate monomer having an ionic group, and said water-soluble multi-functional acrylate monomer in water and at least partially polymerizing said monomers to form said aqueous medium 
     
     
         18 . The process according to  claim 17 , wherein said aqueous medium further comprises a pH adjusting agent. 
     
     
         19 . A process, which comprises applying the aqueous slurry of  claim 1 , to a substrate and drying the slurry to thereby release said oily medium onto said substrate. 
     
     
         20 . The process according to  claim 19 , wherein said oily medium comprises a pesticide or herbicide, or both, and said substrate is soil or vegetation.