High strength microcapsules

Abstract

High strength, high integrity microcapsules containing a hydrophobic core material wherein said microcapsule walls are formed of copolymers of select monomers through a multistep oil-in-water emulsification polymerization process.

We claim: 
     
         1 . A method of making a consumer product comprising combining a consumer product ingredient and microcapsules comprising a high strength wall material and an encapsulated hydrophobic core material said microcapsules being made by a method comprising (a) forming a dispersion of an oil phase composition comprising a hydrophobic core material and one or more polymerizable ethylenically unsaturated monomers, the core monomer, that are wholly or partially soluble in the hydrophobic core material in a water or water-based solution, the continuous phase, said continuous phase, also referred to as the water phase composition, comprising water and at least one or more ethylenically unsaturated polymerizable monomers, the water phase monomer, all or a portion of which are poor to moderately hydrophilic, (b) subjecting the dispersion to one or more conditions that initiate or effectuate the polymerization of the water phase monomer and the core monomer, (c) maintaining the dispersion under such conditions so as to continue polymerization of the monomers until such time as the full capsule walls are formed and, optionally, thereafter (d) isolating the formed microcapsules from the continuous phase. 
     
     
         2 . The method of  claim 1  wherein each of the oil phase composition and the water phase composition contains at least one initiator for effecting or initiating the polymerization of the monomers of each phase. 
     
     
         3 . The method of  claim 1  wherein prior to or concurrent with step (a), either the oil phase composition, the water phase composition, or both is subjected to such conditions as will induce oligomerization/prepolymerization, in whole or in part, of one or more of the monomers of said composition. 
     
     
         4 . The method of  claim 3  wherein each phase to be subjected to oligomerization/prepolymerization contains at least two initiators, at least one of which is activated by conditions different from the other, and which initiates said oligomerization/prepolymerization. 
     
     
         5 . The method of  claim 3  wherein core monomers are subjected to said oligomerization/prepolymerization. 
     
     
         6 . The method of  claim 3  wherein both the core monomers and the water phase monomers are subjected to said oligomerization/prepolymerization. 
     
     
         7 . The method of  claim 1  wherein step (b) comprises a two or more step polymerization process wherein in a first step at least one of the core monomer and the water phase monomer or both is subjected to conditions that initiate or effectuate the oligomerization or pre-polymerization of, in whole or in part, one or more of said core monomer, water phase monomer, or both, and in a second or subsequent step the dispersion is subjected to one or more conditions that initiates or effectuates the full polymerization of the polymerizable monomers including the oligomers/prepolymers and any remaining monomer of the oligomerization/pre-polymerization step. 
     
     
         8 . The method of  claim 7  wherein each phase to be subjected to oligomerization/prepolymerization contains at least two initiators, at least one of which is activated by conditions different from the other, and which initiates said oligomerization/prepolymerization. 
     
     
         9 . The method of  claim 7  wherein the emulsion is subjected to conditions that induce or promote the movement of the so formed oligomers/prepolymers to the oil phase/water phase interface concurrent with or subsequent to the oligomerization/prepolymerization step. 
     
     
         10 . The method of  claim 7  wherein the core monomers are subjected to conditions that effectuate the oligomerization or prepolymerization thereof. 
     
     
         11 . The method of  claim 7  wherein both the core monomers and the water phase monomers are subjected to conditions that effectuate the oligomerization or prepolymerization thereof. 
     
     
         12 . The method of  claim 11  wherein the conditions which effect oligomerization and/or prepolymerization of the monomers of each phase is the same and said oligomerization or pre-polymerization occurs concurrently in each phase. 
     
     
         13 . The method of  claim 11  wherein the conditions which effect oligomerization and/or prepolymerization are different and occur in sequence. 
     
     
         14 . The method of  claim 7  wherein following completion of the oligomerization/pre-polymerization step, the dispersion is subjected to such conditions as will initiate or effectuate the full polymerization of the monomers, including the already formed oligomers and prepolymers, and building of the microcapsule wall or shell at the interface of the oil phase composition and the continuous phase. 
     
     
         15 . The method of  claim 14  wherein full polymerization is concurrently initiated in both the oil phase and the water phase. 
     
     
         16 . The method of  claim 14  wherein polymerization of the monomers and/or oligomers/prepolymers of one phase relative to the other is staggered. 
     
     
         17 . The method of  claim 16  wherein the stagger is such that capsule wall is only partially formed prior to initiation of polymerization of the monomers and/or oligomers/prepolymers of the other phase. 
     
     
         18 . The method of  claim 16  wherein a seed capsule is formed of the first initiated monomer and/or oligomer/prepolymer which seed capsule still possesses areas of oil phase/water phase interface. 
     
     
         19 . The method of  claim 1  wherein during step (b) the emulsion is subjected to conditions that induce or promote the movement of the polymerizing monomers to the oil phase/water phase interface. 
     
     
         20 . The method of  claim 1  wherein the microcapsules are formed in a sequential manner with at least one of the core phase monomer and water phase monomer, preferably both, undergoing a two-step polymerization whereby oligomerization/prepolymerization of each monomer material is initiated and maintained for a period of time in their respective phases and full polymerization of each occurs subsequently at the oil phase/water phase interface, with the oligomers/prepolymers continuing to build upon the wall as it forms: the core phase monomers building on the inner surface of the shell and the water phase monomers building upon the outer surface of the shell. 
     
     
         21 . The method of  claim 1  wherein the core material is selected from UV absorbers, UV reflectors, pigments, dyes, colorants, scale inhibitors, corrosion inhibitors, antioxidants, pour point depressants, waxes, deposition inhibitors, dispersants, flame retardants, biocides, active dye tracer materials, odor control agents, natural oils, flavor and perfumes oils, crop protection agents, and phase change materials. 
     
     
         22 . The method of  claim 1  wherein the core material is a phase change material. 
     
     
         23 . The method of  claim 1  wherein the water phase monomers comprise 1-100 wt % of at least one ethylenically unsaturated monomer manifesting poor to moderately hydrophilic properties; 0-99 wt % of at least one polyfunctional ethylenically unsaturated monomer, and 0-60 wt % of other mono-functional monomers and the core monomers comprise one or more mono-, di- and/or poly-functional ethylenically unsaturated monomers, provided at least 50 mole % of the core monomer is a difunctional monomer having a water solubility of not more than about 1 g/L water as measured in deionized water at 20° C.