IMPROVEMENTS IN OR RELATING TO ORGANIC COMPOUNDS

Abstract

Disclosed is a consumer product comprising a plurality of microcapsules dispersed in a dispersing medium. The microcapsules comprise a core and a shell around the core. The core comprises at least one functional material. The shells of the microcapsules are coated with chitosan. The dispersing medium comprises additional free chitosan. Disclosed is also a method for making such a consumer product, a method for enhancing the deposition and rinse resistance of a plurality of microcapsules dispersed in a dispersing medium and a use of chitosan for enhancing the deposition and rinse resistance of a plurality of microcapsules dispersed in a dispersing medium.

Claims

1. A consumer product comprising a plurality of microcapsules dispersed in a dispersing medium, the microcapsules comprising a core and a shell around the core, the core comprising at least one functional material, wherein the shells of the microcapsules are coated with chitosan and wherein the dispersing medium comprises additional free chitosan.

2. The consumer product according to claim 1, wherein the free chitosan comprised in the dispersing medium has a deacetylation grade higher than 60%.

3. The consumer product according to claim 1, wherein the free chitosan comprised in the dispersing medium has a molecular weight between 500,000 and 5,000,000 g/mol.

4. The consumer product according to claim 1, wherein the chitosan that is coating the shells of the microcapsules has a deacetylation grade between 60% and 100%.

5. The consumer product according to claim 1, wherein the chitosan that is coating the shells of the microcapsules and the free chitosan comprised in the dispersing medium have different average molecular weights.

6. The consumer product according to claim 1, wherein the chitosan that is coating the shells of the microcapsules has a molecular weight between 3,000 and 1,000,000 g/mol.

7. The consumer product according to claim 1, wherein the coated microcapsules have a zeta potential of: Between 0 mV and +50 mV, at a pH of 4 and an ion concentration of 0.001 mol/L; Between −20 mV and +20 mV, at a pH 5.4 and ion concentration of 0.001 mol/L; Less than −20 mV, at a pH of 7 and an ion concentration of 0.001 mol/L.

8. The consumer product according to claim 1, wherein the coated microcapsules have a volume-average size from 0.5 to 25 micrometers.

9. The consumer product according to claim 1, wherein the dispersing medium additionally comprises an anionic surfactant.

10. The consumer product according to claim 1, wherein the shells of the microcapsules comprise a thermosetting resin selected from the group consisting of an aminoplast resin, a polyurea resin, a polyurethane resin, a polyacrylate resin and mixtures thereof.

11. The consumer product according to claim 1, comprising from 0.01 to 5 wt.-% microcapsules, referred to the total weight of the consumer product.

12. The consumer product according to claim 1, comprising from 0.00001 to 0.005 wt.-% free chitosan, referred to the total weight of the consumer product.

13. A method of making a consumer product comprising the steps of: Providing a plurality of microcapsules, the microcapsules comprising a core and a shell around the core, the core comprising at least one functional material; Providing a dispersing medium; Dispersing the microcapsules in the dispersing medium; Coating the plurality of core-shell microcapsules with chitosan to obtain a plurality of coated core-shell microcapsules; Adding additional free chitosan to the dispersing medium.

14. A method of enhancing the deposition and rinse resistance of a plurality of microcapsules dispersed in a dispersing medium on a surface, the microcapsules comprising a core and a shell around the core, the core comprising at least one functional material, the method comprising the steps of: Coating the plurality of core-shell microcapsules with chitosan to obtain a plurality of coated core-shell microcapsules; Adding additional free chitosan to the dispersing medium.

15. (canceled)

Description

EXAMPLES

Example 1: Microcapsule Coating with Chitosan C1

[0087] Aminoplast microcapsules encapsulating a core comprising a fragrance material as functional material were prepared according to the method disclosed as process P5.1 in EP 2 111 214 B1. The volume average diameter of the microcapsules, as measured by light scattering, was 10±0.5 micrometres. The solid content of the slurry was 42 wt %, which corresponds to 35.5 wt % encapsulated perfume.

[0088] These microcapsules were coated with chitosan C1 by performing the steps of: [0089] a) Adjusting the pH of microcapsule slurry to a value of 3.5±0.2; [0090] b) Adding slowly a known amount of chitosan C1, as reported in Table 1, in powder form to 1000 g of the microcapsule slurry under stirring and over a period of time of 15 minutes and adjusting the pH to a value of 5±0.2; [0091] c) Maintaining the resulting mixture for 6 hours at room temperature, in order to obtain a slurry of chitosan-coated microcapsules.

[0092] This procedure was repeated with different amounts of chitosan C1, so that the ratio chitosan C1 content to functional material content of the slurry (referred to as chitosan to functional material ratio hereinafter) was varied from 0.007 to 0.13 [samples 1.1 to 1.10]. This ratio is used here for the sake of simplicity, considering that the functional material is almost quantitatively encapsulated and therefore varies linearly with the weight of the formed microcapsules.

TABLE-US-00001 TABLE 1 Initial chitosan to encapsulated functional material ratio Sample 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 Initial chitosan 0.007 0.01 0.014 0.021 0.028 0.042 0.056 0.07 0.098 0.133 to functional material ratio Supernatant None None None Bluish Blue Blue Blue Blue Blue Blue coloration (example 3)

Example 2: Determination of the Optimal Chitosan Coating

[0093] Samples 1.1 to 1.10 were ultracentrifuged and the pH of their supernatant increased to 6.5 by adding NaOH. Then, 5 ml of a 2 wt % of ninhydrin in deionized water were admixed with 5 ml of supernatant. The development of a velvet color in the mixture is the sign of the presence of free unprotonated amine functional groups and therefore of the presence of free chitosan in the supernatant. On the other hand, the presence of free chitosan in the supernatant is a sign that the surface of the microcapsules is saturated by adsorbed chitosan and fully coated. The onset of the ninhydrin-amine complex can be taken as the point where the optimal chitosan to functional material ratio for quantitative coating has been exceeded. The optimal chitosan to functional material ratio is almost independent of the source, molecular weight and deacetylation grade of chitosan C1 (Table 1). Oppositely, the zeta potential at pH 4 depends on these parameters (see Table 2). It is also observed that the value of the zeta potential reaches a plateau once the quantitative coating has been reached, which confirms that the surface of the capsules is effectively saturated with chitosan C1. The value of the zeta potential at plateau is given in Table 2 for the different types of chitosan.

TABLE-US-00002 TABLE 2 Optimal chitosan Cl to perfume ratio and zeta potential at the onset of complete coating (microcapsule diameter: 10 μm) Molecular weight Deacetylation Optimal chitosan of chitosan Cl grade of chitosan Cl to perfume Zeta potential of (average in g/mol, Cl ratio for coated Origin of chitosan as given by the (as given by the quantitative microcapsules at Cl supplier) supplier) coating pH 4 in mV Shrimp 30'000 90% 0.02 +10 ± 5 mV Shrimp 200'000 75-85% 0.02 +25 ± 5 mV Shrimp 1'700'000 90% 0.02 +10 ± 5 mV Mushroom 200'000 80 ± 10 %(*) 0.03 +20 ± 5 mV (*) estimate

Example 3: Preparation of Shampoo Compositions and Deposition Data

[0094] In a first set of experiments, chitosan C1-coated microcapsule slurries were added to a shampoo composition under gentle stirring with a paddle mixer (example 3.3 and 3.4 in table 3).

[0095] In a second set of experiments, 0.005 g of a 2% chitosan C2 solution in deionized water at pH 3.5 were incorporated into 99.995 g of shampoo base under gentle stirring with a propeller and dispersed therein under stirring. Then chitosan C1-coated microcapsule slurries were added under stirring, so that the level of slurry in the shampoo base was 0.5 wt % referred to the total weight of the shampoo base. The characteristics of both chitosan C2 and chitosan C1-coated microcapsule were varied. The mixture was let to macerate overnight before performing the deposition measurements.

[0096] In a fourth set of experiments, comparative samples were prepared with uncoated microcapsules and cationic guars instead of chitosan C2.

[0097] The shampoo was applied on swatches that have been previously wetted with tap water at a temperature of 37° C. The amount of shampoo was 10% of the weight of the swatches. The shampoo application was performed by gently massaging the swatches during 20 seconds, waiting for 1 minute, rinsing the swatches with tap water at a temperature of 37° C. and removing the excess water by sliding each swatch between two fingers vertically from top to bottom. The extent of deposition was determined by image analysis micrographs obtained with a fluorescence light microscope at a magnification of 40×, using Stream Motion software and Hostasol Yellow 3G as fluorescent agent at 0.02 wt % in perfume, 450 nm excitation wavelength and 500 nm emission wavelength. The deposition value and shampoo composition details are reported in Table 3.

[0098] In Table 3, the deposition scores obtained by a combination of chitosan-coated microcapsules and free chitosan, using chitosan with different molecular weights and origins, are compared to the scores obtained with un-coated microcapsules, with cationic microcapsules, with different free cationic polymer (cationic guar) and in the absence of of free chitosan.

TABLE-US-00003 TABLE 3 Shampoo formulations and deposition data Level of free Depos- polymer ition# Nature of polymer Nature of free C2 in capsules/ Sample coating polymer shampoo mm.sup.2 3.1 No coating — — 0.3 ± 0.2 3.2 No coating Shrimp chitosan 0.0001 wt% 0.8 ± 0.4 1'700'000 g/mol 3.3 Cationic aminoplast — — 1.1 ± 0.6 according to WO 2016207180 Al 3.4 Shrimp chitosan — — 1.9 ± 1 30'000 g/mol 3.5 Shrimp chitosan — — 2.5 ± 1 200'000 g/mol 3.6 Shrimp chitosan — — 1.2 ± 0.4 1'700'000 g/mol 3.7 Shrimp chitosan Cationic guar 0.0001 wt% 1.1 ± 0.5 200'000 g/mol > 1'000'000 g/mol 3.8 Shrimp chitosan Shrimp chitosan 0.0001 wt% 2.5 ± 1 200'000 g/mol 200'000 g/mol 3.9 Shrimp chitosan Shrimp chitosan 0.0001 wt% 4.6 ± 1 200'000 g/mol 1'700'000 g/mol 3.11 Mushroom chitosan Shrimp chitosan 0.0001 wt% 4.6 ± 1 200'000 g/mol 1'700'000 g/mol

TABLE-US-00004 TABLE 4 Model shampoo base composition Percentage by weight Ingredient trade name INCI name in shampoo PROPYLENE GLYCOL Propylene Glycol 1.00 JAGUAR C-13S Guar Hydroxypro- 0.25 (ex RHODIA) pyltrimonium Chloride MARLINAT 242/28 Sodium Laureth Sulfate 25.00 (ex SASOL) DEHYTON AB 30 Coco Betaine 5.00 (ex COGNIS) EUPERLAN PK 3000 Glycol distearate, 0.50 (ex COGNIS) Laureth-4 and Cocoamidopropyl Betaine GLYDANT PLUS LIQ DMDM Hydantoin 0.50 (ex LONZA) SODIUM CHLORIDE Sodium Chloride 1.20 BC 2102 (ex BALLU Dimethiconol Emulsion 2.00 CHIMIE) DEIONIZED WATER QSP 100

[0099] As apparent from Table 3, the maximal deposition is obtained by using the combination of capsules coated with 200,000 g/mol chitosan C1 and 1,700,000 g/mol uncoated chitosan C2. This is also confirmed in the case a mushroom chitosan C1 is used as coating. Finally, a high molecular weight cationic guar is ineffective in promoting capsule deposition on hair, compared to chitosan C2.