Organic compounds

Abstract

Disclosed is a process for preparing an encapsulated fragrance composition. The composition comprises a plurality of microcapsules dispersed in a dispersion medium. The microcapsules comprise a core and a shell around the core. The process comprises the consecutive steps of: a) Providing an aqueous phase (I) comprising at least one anionically modified polyisocyanate (A); b) Providing an organic phase (II) comprising at least one fragrance ingredient; c) Mixing the aqueous phase (I) and the an organic phase (II) to obtain a mixture; d) Forming an emulsion comprising droplets of the organic phase (II) in the continuous aqueous phase (I); e) Adding at least one polyfunctional amine; f) Effecting formation of shells around the droplets formed in step d), to obtain a dispersion of microcapsules. The process comprises the additional step of adding a polyisocyanate (B), which is different from polyisocyanate (A).

Claims

1. A process of preparing an encapsulated fragrance composition, the composition comprising a plurality of microcapsules dispersed in a dispersion medium, the microcapsules comprising a core and a shell around the core, the process comprising the consecutive steps of: a) providing an aqueous phase (I) comprising at least one anionically modified polyisocyanate (A); b) providing an organic phase (II) comprising at least one fragrance ingredient; c) mixing the aqueous phase (I) and the organic phase (II) to obtain a mixture; d) forming an emulsion comprising droplets of the organic phase (II) in the continuous aqueous phase (I); e) adding at least one polyfunctional amine; f) effecting formation of shells around the droplets formed in step d), to obtain a dispersion of microcapsules; and, wherein the process comprises the additional step of: adding a polyisocyanate (B), which is different from polyisocyanate (A).

2. The process according to claim 1, wherein polyisocyanate (B) is added during step c).

3. The process according to claim 1, wherein polyisocyanate (B) is added after step c) and before step d).

4. The process according to claim 1, wherein polyisocyanate (B) is added during step d).

5. The process according to claim 1, wherein the anionically modified polyisocyanate (A) is according to Formula (1). ##STR00003##

6. The process according to claim 1, wherein the aqueous phase (I) provided in step a) additionally comprises a dispersion aid different from anionically modified polyisocyanate (A).

7. The process according to claim 1, wherein polyisocyanate (B) is a non-ionic polyisocyanate.

8. The process according to claim 7, wherein the non-ionic polyisocyanate is selected from the group consisting of dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

9. The process according to claim 1, wherein the polyfunctional amine is a polyethyleneimine containing the following repeat units ##STR00004## wherein x is from 8 to 1500; y is from 0 to 10; and z is 2+y.

10. The process according to claim 1, wherein the aqueous phase (I) additionally comprises a cationic polymer.

11. The process according to claim 1, additionally comprising the step of: adding a cationic polymer.

12. The process according to claim 10, wherein the cationic polymer is an ampholytic co-polymer derived from a cationic monomer or a monomer that can form cations and an anionic monomer or a monomer that can form anions.

13. An encapsulated fragrance composition obtainable by a process according to claim 1.

14. A consumer product comprising an encapsulated fragrance composition according to claim 13.

15. The process according to claim 6, wherein the dispersion aid different from anionically modified polyisocyanate (A) is a non-ionic dispersion aid.

16. The process according to claim 12, wherein the cationic monomer is a monomer containing at least one quaternary ammonium group.

17. The process according to claim 12, wherein the anionic monomer or the monomer that can form anions is based on a compound selected from the group consisting of: acrylic acid, methacrylic acid and derivatives thereof.

18. The process according to claim 12, wherein the cationic polymer is additionally derived from a non-ionic monomer.

19. The consumer product according to claim 14 selected from the group consisting of a personal care product, a home care product and a laundry care product.

Description

Example 1: Capsule Synthesis with Poly(Vinylpyrrolidone) as Dispersion AID

(1) An aqueous solution of 130 g of polyvinylpyrrolidone (PVP K60, ex Ashland), 6 g hydrodispersible isocyanate based on hexamethylene diisocyanate (Bayhydur® XP 2547, ex Covestro) and 450 g water was prepared and the pH was adjusted to 9 using buffer salts. 300 g of fragrance to be encapsulated was mixed with the aqueous phase. 25 g of diisocyanate 4,4 dicyclohexylmethanediyle (Desmodur® W1, ex Covestro) was added to this mixture. The resulting mixture was emulsified at room temperature by means of a stirring device. The emulsification process was carried out to the desired droplet size. Then 10 g of polyethyleneimine solution (Lupasol® G100, ex BASF, as purchased) was added in one step. The mixture was heated gradually to 80° C. for 4 h. After the polymerization, 18 g of ammonia solution and 3 g of hydroxyethylcellulose (Natrosol 250HX, ex Ashland) were added. The mixture was then cooled down to room temperature.

(2) An encapsulated fragrance composition was obtained. The volume average capsule size distribution, obtained with light scattering measurements using a Malvern 2000S instrument, was D(50)=16 μm and D(90)=30 μm. The Zeta potential was −5 mV.

Example 2: Comparative Example to Example 1 with the Isocyanates in the Organic Phase (Not According to the Present Invention)

(3) An aqueous solution of 130 g of polyvinylpyrrolidone (PVP K60, ex Ashland was prepared and the pH was adjusted to 9 using buffer salts. A mixture comprising 300 g fragrance to be encapsulated, 20 g Desmodur® W1 and 8 g Bayhydur® XP 2547 was prepared. The aqueous phase and the organic phase were combined and emulsified at room temperature by means of a stirring device. The emulsification process was carried out to the desired droplet size. Then 10 g of polyethyleneimine solution (Lupasol® G100, ex BASF, as purchased) was added in one step. The mixture was heated gradually to 80° C. for 4 h. After the polymerization, 18 g of ammonia solution and 3 g hydroxyethylcellulose (Natrosol™ 250HX, ex Ashland) were added. The mixture was then cooled down to room temperature.

(4) An encapsulated fragrance composition was obtained. The volume average capsule size distribution, obtained with light scattering measurements using a Malvern 2000S instrument, was D(50)=20 μm and D(90)=40 μm with a shell weight. The Zeta potential was −5 mV.

Example 3: Capsule Synthesis with Poly(Vinylpyrrolidone) as Dispersion Aid and Cationic Terpolymer as Deposition Agent

(5) An aqueous solution of 130 g of polyvinylpyrrolidone (PVP K60, ex Ashland), 6 g hydrodispersible isocyanate based on hexamethylene diisocyanate (Bayhydur® XP 2547, ex Covestro) and 450 g water was prepared and the pH was adjusted to 9 using buffer salts. 300 g of fragrance to be encapsulated was mixed with the aqueous phase. 25 g of diisocyanate 4,4 dicyclohexylmethanediyle (Desmodur® W1, ex Covestro) was added to this mixture. The resulting mixture was emulsified at room temperature by means of a stirring device. The emulsification process was carried out to the desired droplet size. Then 10 g of polyethyleneimine solution (Lupasol® G100, ex BASF, as purchased) was added in one step. The reaction mixture was heated gradually to 60° C.) and an aqueous solution of 30 g of a solution of copolymer of methacrylamidopropyltrimethylammonium chloride and acrylic acid (Floset™ DP CAPS 371L, ex SNF, as supplied at 26.5 wt % in water) was added. Then, the reaction mixture was further heated to 80° C. for 2 h. Thereafter, 18 g of ammonia solution and 3 g hydroxyethylcellulose (Natrosol™ 250HX, ex Ashland) were added. The mixture was then cooled down to room temperature.

(6) An encapsulated fragrance composition was obtained. The volume average capsule size distribution, obtained with light scattering measurements using a Malvern 2000S instrument, was D(50)=10 μm and D(90)=30 μm. The Zeta potential was +5 mV.

Example 4: Comparative Example to Example 3 with the Isocyanates in the Organic Phase (Not According to the Present Invention)

(7) An aqueous solution of 130 g of polyvinylpyrrolidone (PVP K60, ex Ashland) and 450 g water was prepared and the pH was adjusted to 9 using buffer salts. A mixture comprising 300 g fragrance to be encapsulated, 20 g Desmodur® W1 and 8 g Bayhydur® XP 2547 was prepared. The aqueous phase and the organic phase were combined and emulsified at room temperature by means of a stirring device. The emulsification process was carried out to the desired droplet size. Then 10 g of polyethyleneimine solution (Lupasol® G100, ex BASF, as purchased) was added in one step. The reaction mixture was heated gradually to 60° C. and an aqueous solution of 30 g copolymer of methacrylamidopropyltrimethylammonium chloride and acrylic acid (Floset™ CAPS 371L, ex SNF, as supplied at 26.5 wt % in water) was added. Then, the reaction mixture was further heated to 80° C. for 2 h. Thereafter, 18 g of ammonia solution and 3 g hydroxyethylcellulose (Natrosol™ 250HX, ex Ashland) were added. The mixture was then cooled down to room temperature.

(8) An encapsulated fragrance composition was obtained. The volume average capsule size distribution, obtained with light scattering measurements using a Malvern 2000S instrument, was D(50)=20 μm and D(90)=40 μm. The solid content of the slurry was 45 wt %. The Zeta potential was +5 mV.

Example 5: Capsule Synthesis with Cationic Copolymer as Templating Agent and the Isocyanates in the Aqueous Phase

(9) An aqueous solution of 100 g of a copolymer of methacrylamidopropyltrimethylammonium chloride and acrylic acid (Floset™ DP CAPS 371L, ex SNF, as supplied at 26.5 wt % in water), 6 g hydrodispersible isocyanate based on hexamethylene diisocyanate (Bayhydur® XP 2547, ex Covestro) and 450 g water was prepared and the pH was adjusted to 9 using buffer salts. 300 g of fragrance to be encapsulated was mixed with the aqueous phase. 25 g of diisocyanate 4,4 dicyclohexylmethanediyle (Desmodur® W1, ex Covestro) was also added to this mixture. The resulting mixture was emulsified at room temperature by means of a stirring device. The emulsification process was carried out to the desired droplet size. Then 10 g of polyethyleneimine solution (Lupasol® G100, ex BASF, as purchased) was added in one step. The mixture was heated gradually to 80° C. for 4 h. After the polymerization, 18 g of ammonia solution and 10 g of a cationic acrylamide (Flosoft™ FS555, ex SNF) were added. The mixture was then cooled down to room temperature.

(10) An encapsulated fragrance composition was obtained. The volume average capsule size distribution, obtained with light scattering measurements using a Malvern 2000S instrument, was D(50)=10 μm and D(90)=30 μm. The Zeta potential (mV) was +30 mV.

Example 6: Comparative Example to Example 5 with the Isocyanates in the Organic Phase (Not According to the Present Invention)

(11) An aqueous solution of 100 g a copolymer of methacrylamidopropyltrimethylammonium chloride and acrylic acid (Floset™ DP CAPS 371L, ex SNF, as supplied at 26.5 wt % in water) and 450 g water was prepared and the pH was adjusted to 9 using buffer salts. A mixture comprising 300 g fragrance to be encapsulated, 20 g Desmodur® W1 and 8 g Bayhydur® XP 2547 was prepared. The aqueous phase and the mixture were combined and emulsified at room temperature by means of a stirring device. The emulsification process was carried out to the desired droplet size. Then 10 g of polyethyleneimine solution (Lupasol® G100, ex BASF, as purchased) was added in one step. The reaction mixture was heated gradually to 80° C. for 4 h. After the interfacial polymerization, 18 g of ammonia solution and 0.4 g Natrosol™ 250HX were added. The mixture was then cooled down to room temperature.

(12) An encapsulated fragrance composition was obtained. The volume average capsule size distribution, obtained with light scattering measurements using a Malvern 2000S instrument, was D(50)=10 μm and D(90)=30 μm. The solid content of the slurry was 45 wt %. The Zeta potential (mV) was +38 mV.

Example 7: Influence of Process on the Stability of the Microcapsules with Respect to Leakage in a Model Extractive Medium

(13) The model extractive medium was a system consisting of 1.8 ml of an aqueous solution of ethanol at an initial concentration of 20 vol % co-existing with 10 ml of an un-miscible cyclohexane phase.

(14) The slurry to be assessed was diluted in such a way that the fragrance concentration in the diluted slurry is about 10 wt % and 200 microliters of this diluted slurry are added to the vial.

(15) The vial was submitted to a horizontal mixing on an elliptic horizontal x,y-mixing equipment operating at a 250 rpm for 4 hours (shaking in the z direction is avoided).

(16) The upper cyclohexane phase containing the extracted fragrance was analysed spectrophotometrically by using a UV/visible light spectrometer. The fragrance concentration was determined by measuring the intensity of the absorbed UV/visible light at the maximum absorbance wavelength, which had been determined previously by using a reference fragrance/cyclohexane solution of known concentration. This latter reference solution was used as an external standard for the quantification of the extracted fragrance. The leakage value is defined as the percentage of the encapsulated fragrance that has been recovered in the hexane phase.

(17) Representative leakage values are given in Table 1 hereunder.

(18) TABLE-US-00001 TABLE 1 Leakage values for different encapsulated fragrance compositions Leakage in model Example extractive medium Example 1 22 +/− 8 wt % Example 2 (comparative) 70 wt % Example 3  33 +/− 17 wt % Example 4 (comparative) 70 wt % Example 5 55 +/− 5 wt % Example 6 (comparative) 70 wt %

(19) From Table 1 it can be seen that adding the polyisocyanates in the aqueous phase instead of pre-dissolving them in the organic (fragrance) phase improves the stability of the microcapsules with respect to leakage in a model extractive medium.

Example 8: Influence of Process on the Olfactive Performance of the Microcapsules

(20) The microcapsules were incorporated in a standard, unfragranced liquid fabric care conditioner stored for one month at 37° C. and 45° C. The amount of microcapsule in the conditioner was 0.5 wt %.

(21) 35 g of the base was used in a side-loaded wash machine (20 L capacity, loaded with 1 kg terry towelling, preferably washed beforehand with an unfragranced laundry detergent); a rinse cycle was performed at a temperature of 20° C., followed by spin drying.

(22) In both laundry rinse and wash cases, the pre-rub olfactive evaluation was performed on wet laundry directly out of the machine and after 4 hours. For this evaluation, the terry towelling was handled carefully in order minimize the risk of breaking the microcapsules mechanically. The post-rub olfactive evaluation was performed after line drying the terry towelling for 24 hours at room temperature. This evaluation was performed by gently rubbing one part of the terry towelling on another part of same terry towelling. The olfactive performance (intensity) has been assessed by a panel of 4 experts rated on a scale of 1-5 (1=barely noticeable, 2=weak, 3=medium, 4=strong and 5=very strong). When relevant, qualitative comments on the perceived odour direction were recorded.

(23) The results of the olfactive performance assessment are reported on Table 2.

(24) TABLE-US-00002 TABLE 2 Olfactive score on dry towel (after 24 hours drying at room temperature) Olfactive performance Olfactive performance after 2 months at 37° C. after 2 weeks at 45° C. Pre-rub Post-rub Pre-rub Post-rub Example score score score score Example 3 2 3 2 3 Example 4 2 3 2 3 (comparative) Example 5 1.2 1.3 0.8 1.1 Example 6 0.7 0.5 0 0 (comparative)

(25) From Table 2 it can be seen that adding the polyisocyanates in the aqueous phase instead of pre-dissolving them in the organic (fragrance) phase has no negative impact on the olfactive performance of the samples after storage. The olfactive stability may even be improved, as in the case of Example 5 vs. Example 6.

Example 9: Surface Tension

(26) The surface tension of aqueous phases comprising various water-dispersible anionically modified isocyanates and/or stabilizing polymers was measured. The measurement was performed by using the so-called pendant drop method. The instrument used was a Drop Shape Analyzer-DSA30 manufactured by Krüss GmbH, Hamburg, Germany. The way the surface tension is calculated by the instrument software is described in Krüss Technical Note TN316e, dated October 2010 and available, for example, under:

(27) https://www.kruss-scientific.com/fileadmin/user_upload/website/literature/kruss-tn316-en.pdf

(28) TABLE-US-00003 TABLE 3 Surface tension Aqueous phase composition Surface tension [mN/m] 13 wt % poly(vinylpyrrolidone) 67.7 +/− 0.3 (PVP) K 60 13 wt % PVP K 60 + 6 wt % 55.8 +/− 0.3 Bayhydur ™ XP2547 10 wt % Floset ™ DP CAPS 371L 51.3 +/− 0.3 10 wt % Floset ™ DP CAPS 371L + 47.6 +/− 0.2 5 wt % Bayhydur ™ XP2547

(29) From Table 3 it can be seen that adding the polyisocyanates in the aqueous phase comprising a stabilizing polymer decreases the surface tension of this aqueous phase. Without being bound by theory, these results support that polyisocyanates added in the water phase are located on the water side of the water/oil interface, where they participate to the emulsification process and are more available for further reaction with the polyamines during the microcapsule formation.

(30) The surface tension results show that the addition of bayhydur XP2547 in the aqueous phase helps to control the particle size of the emulsion, forming smaller particle size (ex 10 μm vs 20 μm).