Process for preparing polyurea microcapsules with improved deposition
The present invention relates to a process for producing perfume- or flavor-containing polyurea microcapsules with improved deposition of encapsulated actives on targeted surfaces such as fiber, hair and skin, which can be used in home or personal care products, as well as to microcapsules obtainable by such a process and consumer products comprising these microcapsules.
1. A process for the preparation of core-shell microcapsules comprising the following steps:
a) dissolving at least one polyisocyanate in an oil phase comprising a perfume; wherein the at least one polyisocyanate is selected from the group consisting of: a polyisocyanurate of toluene diisocyanate, a trimethylol propane-adduct of toluene diisocyanate, a trimethylol propane-adduct of xylylene diisocyanate, a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, a trimethylol propane-adduct of hexamethylene diisocyanate, a biuret of hexamethylene diisocyanate, and mixtures thereof,
b) dispersing the oil phase obtained in step a) into an aqueous solution comprising as an emulsifier a mixture of a neutral polyvinyl alcohol and a cationic polymer selected from the group consisting of quaternized copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate, copolymer of vinylpyrrolidone and methacrylamidopropyl trimethylammonium chloride, polydiallyldimethyl ammonium chloride, copolymer of allyl dimethyl ammonium chloride/acrylamide and copolymer of acrylamidopropyltrimonium chloride and acrylamide; to form an oil-in-water emulsion;
c) adding to the oil-in-water emulsion obtained in step b) a polyvinylamine with a molecular weight equal or higher than 2000 g/mol, followed by a polyamine with a molecular weight lower than 250 g/mol selected from the group consisting of 1,2-diaminopropane, 1,2-diaminoethane, diethylenetriamine, guanidine, and guanidine carbonate, to form a microcapsule slurry.
2. The process according to claim 1 , wherein the polyvinylamine has a molecular weight higher than 50,000 g/mol.
3. The process according to claim 1 , wherein the polyvinylamine and the emulsifier are used in a weight ratio based on dry matter comprised between 0.1 and 10.
4. The process according to claim 1 , wherein the concentration of perfume is comprised between 10% and 60% by weight relative to the total weight of the microcapsule slurry.