SUBMICRONIC EMULSION

Abstract

The invention relates to a process for preparing a dispersion of a lipophilic compound in a continuous hydrophilic phase, the morphology of which is submicronic. During the preparation of this dispersion, there is applied, by means of a device which produces a shearing gradient less than 5000 s.sup.−1, a shear stress from 100 to 5000 Pa during the addition of the lipophilic compound in the continuous phase which comprises a rheology-modifying compound selected from anionic copolymers, preferably an anionic polymer, in particular an ASE polymer or a HASE polymer. The dispersed particles of the lipophilic compound are nanometric particles whose size is less than 1 μm. The dispersion, particularly in the form of an emulsion, can be used in numerous fields.

Claims

1. A method of preparing a dispersion comprising a continuous hydrophilic phase and a lipophilic phase dispersed in the continuous hydrophilic phase in the form of nanometric particles, the method comprising: preparing a mixture comprising a hydrophilic compound and a rheology-modifying compound of the hydrophilic compound, and adding a lipophilic compound in the continuous hydrophilic phase by applying, using a device producing a shear gradient of less than 5,000 s.sup.−1, a stress chosen among a shear stress ranging from 100 to 5,000 Pa and an extensional stress ranging from 100 to 5,000 Pa, wherein the continuous hydrophilic phase comprises the hydrophilic compound and the rheology-modifying compound, and the rheology-modifying compound is a anionic copolymer.

2. The method according to claim 1, wherein: the continuous hydrophilic phase has a viscosity ranging from 20 to 50,000 mPa.Math.s; the dispersion has a viscosity ranging from 20 to 50,000 mPa.Math.s; the dispersion is an emulsion; or the dispersion comprises from 0.1 to 75% by weight of dispersed lipophilic phase relative to the total amount by weight of the continuous hydrophilic phase and of the dispersed lipophilic phase.

3. The method according to claim 1, wherein the hydrophilic compound is chosen among water alone or in combination with at least one compound chosen among glycerol, polyglycerols, glycols, moistening compounds, sugar derivatives, and coalescing agents.

4. The method according to claim 1, wherein the rheology-modifying compound has a pH greater than 5; or the rheology-modifying compound is at least one selected from the group consisting of an ASE copolymer and a HASE copolymer.

5. The method according to claim 1, wherein the mixture also comprises a base; the mixture has a pH greater than 5; the mixture has a pH of less than 12; the mixture has a pH ranging from 5 to 12; the mixture does not comprise any surface-active compound or comprises a small amount.

6. The method according to claim 1, wherein the mixture comprises from 0.5 to 15% by weight of a rheology modifier.

7. The method according to claim 1, wherein: the preparation temperature is lower than a boiling point of the continuous hydrophilic phase and lower than a boiling point of the lipophilic phase; the preparation temperature is higher than a melting point of the continuous hydrophilic phase and higher than a melting point of the lipophilic phase; or the preparation temperature is lower than the boiling point of the continuous hydrophilic phase and lower than the boiling point of the lipophilic phase while being higher than the melting point of the continuous hydrophilic phase and higher than the melting point of the lipophilic phase.

8. The method according to claim 1, wherein the dispersion is an emulsion of a dispersed lipophilic phase in the continuous hydrophilic phase.

9. The method according to claim 1, wherein the shear stress or the extensional stress ranges from 300 to 5,000 Pa; the shear stress or the extensional stress is also applied when preparing the mixture; or the stress is applied using a device that produces a shear gradient of less than 2,000 s.sup.−1 or using a device that produces a shear gradient ranging from 100 to 5,000 s.sup.−1.

10. The method according to claim 1, wherein a mean size (measured by light scattering) of dispersed particles of lipophilic phase is submicronic.

11. The method according to claim 1, further comprising: neutralisation of the dispersion; or partial coacervation of the rheology-modifying compound.

12. A dispersion prepared by the method according to claim 1.

13. A product comprising the dispersion according to claim 12.

14. An article, comprising the dispersion according to claim 12 wherein the article is selected from the group consisting of cosmetics, paints, dyes, printing, inks, construction, fuels, lubricants, anti-foaming agents, metallurgy, fertilisers, pharmaceuticals, agro-chemicals, crop protection products, detergents, food, leather, and coating.

Description

EXAMPLES

Example 1: Preparation of Rheology-Modifying Compounds According to the Invention

[0118] 474.9 g of bi-permuted water, 6.51 g of sodium dodecyl sulphate (SDS) and 5.45 g of tridecyl alcohol tri-ethoxylate (Rhodasurf ID 030, Solvay) are introduced into a polymerisation reactor. The reactor is placed under stirring and heated to 76° C.

[0119] 153 g of bi-permuted water, 2.28 g of sodium dodecyl sulphate, 0.163 g of n-dodecyl mercaptan, 109.04 g of ethyl acrylate (EA) as compound (a2), 112.5 g of methacrylic acid (MAA) as compound (a1), 45.31 g of methyl methacrylate as other compound (a2), 13.445 g of branched C.sub.16 (25 EO) methacrylate as compound (a3) of formula (I) wherein R.sup.1 represents a methacrylate group, R.sup.2 represents a branched C.sub.16-alkyl group, m=25 and n=0, 13.445 g of branched C.sub.12 (30 EO) methacrylate as other compound (a3) of formula (I) wherein R.sup.1 represents a methacrylate group, R.sup.2 represents a branched C.sub.12-alkyl group, m=30 and n=0, are weighed separately in a beaker. This mixture is placed under stirring with a magnetic bar.

[0120] A mixture containing 0.925 g of ammonium persulphate and 4.07 g of bi-permuted water and a second mixture consisting of 0.093 g of sodium bisulphite and 4.88 g of bi-permuted water are simultaneously added to the reactor. The mixture is then injected over a period of two hours. The temperature is kept at 76° C.

[0121] Polymer (P1) is obtained according to the proportions shown in Table 1 in which the values are weight ratios.

[0122] Similarly, polymers (P2), (P3), for which (a3) is a compound of formula (I) in which R.sup.1 represents a methacrylate group, R.sup.2 represents a tristyryl phenyl (TSP) group, m=25 and n=0, and (P4) are prepared according to the proportions (in dry g/dry weight) shown in Table 1. The total amount of monomers is 100% by weight and the amount of chain transfer agent is relative to the total amount by weight of monomers.

TABLE-US-00001 TABLE 1 rheology-modifying polymer P1 P2 P3 P4 a1: MAA 37.92 36.74 40.31 0.49 a1: AA / / / 36.99  a2: MMA 15.58 27.03 / / a2: EA 37.50 27.03 49.73 53.21  a3: branched C.sub.12 (30 EO) methacrylate  4.50 / / / a3: branched C.sub.16 (25 EO) methacrylate  4.50  9.21 / 8.21 a3: TSP (25 EO) methacrylate / /  8.04 / a4: AMPS / /  1.92 1.09 transfer agent: n-dodecyl mercaptan  0.06  0.29 / /

Example 2: Preparation of Dispersions According to the Invention

[0123] A continuous hydrophilic phase mixture (M) is prepared from rheology-modifying polymer, water and optionally from an additional hydrophilic compound and optionally from a non-ionic surface-active compound (SA) chosen among Plantaren 2000 N UP (BASF), Sensient LRT (Sensient Cosmetic Technologies), Rhodasurf ID 030 (Solvay), Polysorbate 20 (Sigma-Aldrich) and Disponil G625 (BASF).

[0124] A base is added and the mixture is placed under stirring until a homogenous aqueous mixture is obtained.

[0125] The lipophilic compound to be dispersed is prepared separately.

[0126] The lipophilic phase is then introduced, under stirring using a mixer, into the continuous hydrophilic phase to produce an emulsion.

[0127] As applicable, an acid or saline coacervation agent (acid diluent or saline diluent) is added.

[0128] Dispersions of different lipophilic compounds or mixtures of lipophilic compounds were prepared: alkyd resin 1 (viscosity 500,000 mPa.Math.s at 70° C.), alkyd resin 2 (viscosity 6,550 mPa.Math.s at 70° C.), alkyd resin 3 (viscosity 230 mPa.Math.s at 70° C.), mixture of alkyd resin 1 and linoleic acid (viscosity 8,000 mPa.Math.s at 70° C.), sunflower oil (viscosity 560 mPa.Math.s at room temperature), n-octyltriethoxysilane (viscosity 16.7 mPa.Math.s at room temperature).

[0129] Dispersions according to the invention are obtained according to the amounts (g) and characteristics shown in Tables 2 to 7 and for which the particle size of the dispersed lipophilic compound is less than 1 μm.

TABLE-US-00002 TABLE 2 Dispersion D1 D2 D3 D4 D5 raw materials polymer P1 P2 P2 P2 P3 other compound or SA / SDS / / / base NaOH NaOH NaOH NaOH NaOH acid H.sub.3PO.sub.4 H.sub.3PO.sub.4 H.sub.3PO.sub.4 H.sub.3PO.sub.4 / salt CaCl.sub.2 CaCl.sub.2 CaCl.sub.2 CaCl.sub.2 / lipophilic compound: 1 1 2 3 1 alkyd resin emulsification mixer (at 500 s.sup.−1) VMI Rayneri temperature 60-70° C. continuous dry polymer 4.341 4.356 4.356 4.356 4.356 hydrophilic other dry compound or dry SA / 0.25 / / / phase water 47.699 45.176 45.176 45.176 45.176 dry base 0.53 0.468 0.468 0.468 0.468 pH 6 +/− 0.3 polymer (% by weight) 8.26 8.67 8.71 8.71 8.71 stress (Pa) 900 300 500 500 300 dispersed lipophilic compound 77.9 75 75 75 75 acid diluent water 29.702 25.152 25.152 25.152 / acid 0.052 0.048 0.048 0.048 / saline diluent water 14 14 14 14 / salt 0.07 0.07 0.07 0.07 / particle size D50% (μm) 0.9 0.8 0.6 0.5 0.9 D40% (μm) 0.5 0.4 0.5 0.5 0.5 D30% (μm) 0.4 0.3 0.5 0.5 0.4

TABLE-US-00003 TABLE 3 Dispersion D6 D7 D8 raw material polymer P1 P2 P2 other compound or SA Disponil G625 base NaOH AMP AMP acid HCl H.sub.3PO.sub.4 D-gluconic acid salt / / / lipophilic compound: 1 1 1 alkyd resin emulsification mixer (at 500 s.sup.−1) VMI Rayneri PC Laborsystem temperature 60-70° C. continuous dry polymer 5.64 3.843 19.335 hydrophilic other dry compound or dry 0.4 0.88 4.4 phase water 75.06 30.4845 152.5125 dry base 0.6 0.9025 4.5125 pH 6 +/− 0.3 polymer (% by weight) 6.90 10.64 10.70 stress (Pa) unavailable dispersed lipophilic compound 150 75 375 acid diluent water 40.048 25.0272 190 acid 0.092 0.0428 4.15 saline diluent water / 24 / salt / 0.07 / particle size D50% (μm) 0.5 0.5 0.4 D40% (μm) 0.4 0.4 0.3 D30% (μm) 0.3 0.3 0.2 *with no alkyd resin, incremental addition

TABLE-US-00004 TABLE 4 Dispersion D9 D10 D11 raw material polymer P2 P2 P2 other compound or SA Disponil G625 Polysorbate 20 tributyl 2-acetylcitrate base AMP NaOH AMP acid ascorbic acid / D-gluconic acid salt / NaCl / lipophilic compound: 1 sunflower oil* 1 alkyd resin emulsification mixer (at 500 s.sup.−1) VMI Rayneri PC Laborsystem VMI Rayneri temperature 60-70° C. room temperature 60-70° C. continuous dry polymer 3.93 22.71 3.7792 hydrophilic other dry compound or dry SA 0.88 4.1 0.39 phase water 30.3975 188.93 32.9008 dry base 0.9025 2.56 0.912 pH 6 +/− 0.3 polymer (% by weight) 10.88 10.40 10.00 stress (Pa) unavailable dispersed lipophilic compound 75 410 75 acid diluent water 38 / 38 acid 0.435 / 0.83 saline diluent water 20 450 / salt / 3.1 / particle size D50% (μm) 0.5 0.9 0.9 D40% (μm) 0.4 0.8 0.4 D30% (μm) 0.3 0.6 0.3 *with no alkyd resin, incremental addition

TABLE-US-00005 TABLE 5 Dispersion D12 D13 D14 D15 raw materials polymer P2 P2 P2 P2 other compound or SA / / Rhodasurf ID 030 / base NaOH acid H.sub.3PO.sub.4 / salt CaCl.sub.2 NaCl lipophilic compound: 1 Linoleic acid 1 sunflower oil* alkyd resin (30%) + (70%) emulsification mixer (at 500 s.sup.−1) PC Laborsystem VMI Rayneri PC Laborsystem temperature 60-70° C. room temperature continuous dry polymer 21.75 4.356 4.356 22.71 hydrophilic other dry compound or dry SA / / 0.7 / phase water 225.95 45.176 45.176 188.93 dry base 2.3 0.468 0.468 2.56 pH 6 +/− 0.3 polymer (% by weight) 8.70 8.71 8.59 10.60 stress (Pa) 500 500 1,700 600 dispersed lipophilic compound 376.2 75 75 434 acid diluent water 125.26 25.152 25.152 / acid 0.24 0.048 0.048 / saline diluent water 70 14 14 450 salt 0.35 0.07 0.07 3 particle size D40% (μm) 0.8 0.9 0.9 0.9 D30% (μm) 0.5 0.4 0.4 0.7 *with no alkyd resin, incremental addition

TABLE-US-00006 TABLE 6 Dispersion D16 D17 D18 raw material polymer P2 P2 P2 other compound or SA / / / base NaOH acid H.sub.3PO.sub.4 / salt / CaCl.sub.2 / lipophilic compound: 1 1 n-octyltriethoxysilane* alkyd resin emulsification mixer (at 500 s.sup.−1) PC Laborsystem VMI Rayneri temperature 60-70° C. room temperature continuous dry polymer 21.75 24.06 2.28 hydrophilic other dry compound or dry SA / / / phase water 225.95 250.59 24.84 dry base 2.3 2.55 0.26 pH 6 +/− 0.3 polymer (% by weight) 8.70 8.68 8.33 stress (Pa) 500 500 300 dispersed lipophilic compound 377.7 521 31.8 acid diluent water 124.76 244.132 / acid 0.24 0.268 / saline diluent water / 70 / salt / 0.42 / diluent water / / 31 particle size D30% (μm) 0.8 0.9 0.8 *with no alkyd resin, incremental addition

TABLE-US-00007 TABLE 7 Dispersion D19 D20 D21 raw materials polymer P4 P2 P2 other compound or SA / Plantaren 2000 N UP Sensient LRI base NaOH acid H.sub.3PO.sub.4 / / salt CaCl.sub.2 NaCl lipophilic compound: 1 sunflower oil* alkyd resin emulsification mixer (at 500 s.sup.−1) PC Laborsystem temperature 60-70° C. room temperature continuous dry polymer 22.477 23.34 22.71 hydrophilic other dry compound or dry SA / 2 1.19 phase water 238.943 187.16 188.93 dry base 3.78 2.6 6.4 pH 6 +/− 0.3 polymer (% by weight) 8.48 10.85 10.54 stress (Pa) unavailable dispersed lipophilic compound 376.2 431.1 447 acid diluent water 206.712 / / acid 4.388 / / saline diluent water 70 453.1 450 salt 0.35 3 3.2 particle size D30% (μm) 0.9 0.8 0.8 *with no alkyd resin, incremental addition

[0130] The method according to the invention makes it easy to prepare, using a conventional mixer producing a low shear gradient, emulsions of various lipophilic compounds dispersed in a continuous hydrophilic phase for which the size of the particles of lipophilic compound is well below 1 μm.