Process for preparing polyurea microcapsules
The present invention relates to a process for producing perfume-containing microcapsules with a polyurea wall that can be used in home or personal care products, as well as to the microcapsules themselves and consumer products that include or incorporate these microcapsules. The process of the invention uses a particular colloidal stabilizer in the form of an aqueous solution that includes defined proportions of particular polymers.
1. A process for the preparation of polyurea microcapsules which consists essentially of:
dissolving at least one polyisocyanate having at least two isocyanate groups in a perfume to form a first mixture;
adding to the first mixture a colloidal stabilizer in the form of an aqueous solution comprising: from 0.1% to 0.4% of a polyvinyl alcohol and from 0.6% to 1% of a cationic copolymer of vinylpyrrolidone and of a quaternized vinylimidazol, with the percentages being defined by weight relative to the total weight of the colloidal stabilizer to form a second mixture; and
adding to the second mixture a reactant selected from the group consisting of water soluble guanidine salts and guanidine and reacting the reactant with the second mixture under conditions sufficient to form microcapsules having a polyurea wall with the polyisocyanate.
2. The process according to claim 1 , wherein the cationic copolymer of vinylpyrrolidone and of a quaternized vinylimidazol is a copolymer of vinylpyrrolidone and quaternized vinylimidazol in an aqueous solution.
3. The process according to claim 1 , wherein the polyisocyanate comprises at least three isocyanate functional groups.
4. The process according to claim 1 , wherein the polyisocyanate is a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, or a biuret of hexamethylene diisocyanate.
5. The process according to claim 1 , wherein the reactant is guanidine carbonate.
6. The process according to claim 1 , wherein the perfume has a concentration of 28 to 60% by weight relative to the total weight of the microcapsules.
7. The process according to claim 1 , wherein the perfume contains less than 5% of its own weight of primary alcohols, less than 10% of its own weight of secondary alcohols and less than 15% of its own weight of tertiary alcohols.
8. The process according to claim 1 , wherein at least 50% of the perfume consists of perfuming ingredients selected from one or more of the following groups:
Group 1: perfuming ingredients comprising a cyclohexyl, cyclohexenyl, cyclohexanone or cyclohexenone ring substituted with at least one linear or branched C 1 to C 4 alkyl or alkenyl substituent;
Group 2: perfuming ingredients comprising a cyclopentyl, cyclopentenyl, cyclopentanone or cyclopentenone ring substituted with at least one linear or branched C 4 to C 8 alkyl or alkenyl substituent;
Group 3: perfuming ingredients comprising a phenyl ring or perfuming ingredients comprising a cyclohexyl, cyclohexenyl, cyclohexanone or cyclohexenone ring substituted with at least one linear or branched C 5 to C 8 alkyl or alkenyl substituent or with at least one phenyl substituent and optionally one or more linear or branched C 1 to C 3 alkyl or alkenyl substituents;
Group 4: perfuming ingredients comprising at least two fused or linked C 5 and/or C 6 rings;
Group 5: perfuming ingredients selected from the group consisting of camphor, borneol, isobornyl acetate, 8-isopropyl-6-methyl-bicyclo[2.2.2]oct-5-ene-2-carbaldehyde, camphopinene, cedramber (8-methoxy-2,6,6,8-tetramethyl-tricyclo[5.3.1.0(1,5)]undecane), cedrene, cedrenol, cedrol, mixture of 9-ethylidene-3-oxatricyclo[6.2.1.0(2,7)]undecan-4-one and 10-ethylidene-3-oxatricyclo[6.2.1.0(2,7)]undecan-4-one, and 3-methoxy-7,7-dimethyl-10-methylene-bicyclo[4.3.1]decane;
Group 6: perfuming ingredients comprising at least one C 7 to C 20 ring structure; and
Group 7: perfuming ingredients having a logP value above 3.5 and comprising at least one tert-butyl or at least one trichloromethyl substituent;
wherein the percentages are defined by weight, relative to the total weight of the perfume.
9. The process according to claim 8 , wherein at least 50% of the perfume consists of perfuming ingredients selected from any one or more of Groups 3 to 7.
10. The process according to claim 9 , wherein at least 50% of the perfume consists of perfuming ingredients selected from any one or more of Groups 3, 4, 6 or 7.
11. The process according to claim 1 , wherein the perfume comprises at least 50% of perfuming ingredients having a logP above 3, wherein the percentages being defined by weight relative to the total weight of the perfume.