Encapsulated Essential Oils

Abstract

A process for the preparation of essential oil microcapsules including dissolving a di- or polyisocyanate into an essential oil, emulsifying the resulting mixture in an aqueous solution containing a di- or polyamine, and or a di or polyhydroxy compound to effect encapsulation of the essential oil through interfacial polymerization, whereby there is formed a polyurea and/or polyurethane film around the essential oil droplets which film enhances the stability of the essential oil, reduces its evaporation rate and controls its release rate when applied to a substrate.

What is claimed is: 
     
         1 . A microcapsule comprising a polyurea and/or polyurethane film encapsulating a volatile essential oil, the polyurea and/or polyurethane film having a permeability providing sustained release of the essential oil, wherein the encapsulated essential oil, upon release, is capable of serving as a disinfectant, a pesticide, an insect repellant, an antiviral agent, an antifungal agent or any combination thereof. 
     
     
         2 . The microcapsule of  claim 1 , wherein the essential oil is encapsulated together with an agent capable of enhancing the properties of the essential oil. 
     
     
         3 . The microcapsule of  claim 3 , wherein the agent comprises sesame oil. 
     
     
         4 . The microcapsule of  claim 1 , wherein the essential oil is selected from the group consisting of cinnamon, cedar, clove, geranium, lemongrass, linseed, sesame, thyme, rosemary, anise, basil, camphor, citronella, eucalyptus, fennel, grapefruit, lemon, mandarin, orange, pine needle, pepper, rose, tangerine, tea tree, tea seed, caraway, garlic, peppermint, onion, lavender, almond, spearmint and mixtures thereof. 
     
     
         5 . The microcapsule of  claim 1 , wherein the microcapsule has a size in the range of 0.5-100 microns. 
     
     
         6 . The microcapsule of  claim 5 , wherein the microcapsule has a size in the range of 20-100 microns. 
     
     
         7 . The microcapsule of  claim 1 , wherein the polyurea and/or polyurethane film protects against oxidation and/or evaporation of the encapsulated essential oil. 
     
     
         8 . The microcapsule of  claim 1 , wherein the microcapsule is biodegradable. 
     
     
         9 . The microcapsule of  claim 1 , wherein the microcapsule has a zero-order release rate. 
     
     
         10 . The microcapsule of  claim 1 , wherein the polyurea and/or polyurethane film comprises 5%-35% by weight of the microcapsule. 
     
     
         11 . The microcapsule of  claim 10 , wherein the polyurea and/or polyurethane film comprises 10%-25% by weight of the microcapsule. 
     
     
         12 . The microcapsule of  claim 1 , wherein the volatile essential oil comprises 60%-95% by weight of the microcapsule. 
     
     
         13 . A formulation comprising a plurality microcapsules having a polyurea and/or polyurethane film encapsulating a volatile essential oil, the film having a permeability facilitating sustained release of the essential oil; wherein the encapsulated essential oil, upon release, is capable of serving as a disinfectant, a pesticide, an insect repellant, an antiviral agent, an antifungal agent or any combination thereof. 
     
     
         14 . The formulation of  claim 13 , further comprising an anionic, cationic, amphoteric or non-charged hydrophilic surfactant. 
     
     
         15 . The formulation of  claim 13 , further comprising a suspending agent and/or an emulsifier capable of preventing and/or reducing microcapsule aggregation. 
     
     
         16 . The formulation of  claim 15 , wherein the emulsifier is selected from the group consisting of sodium, potassium, magnesium, calcium or ammonium salts of lignin sulfonate, low density polyvinylalcohol, high density polyvinylalcohol, Tween 20, Tween 40 and Tween 80. 
     
     
         17 . The formulation of  claim 15 , wherein the suspending agent is selected from the group consisting of carboxymethyl cellulose, sodium salt, Xanthan gum, Karya gum, Locust bean gum, polyvinylpyrrolidone (PVP), water soluble polyvinyl alcohol (PVA), poly(ethoxy)nonylphenol, polyether block polymers, polyoxyethylene adducts of fatty alcohols and esters of fatty acids.