METHOD FOR PRODUCING EMULSIONS

Abstract

The invention relates to a method for preparing emulsions.

In order to create a new method for preparing emulsions, in which homogenous oil droplets as small as possible can be generated with an energy input as low as possible, it is proposed in the scope of the invention, that at least two liquid streams of liquids that cannot be intermixed with one another are pumped through separate openings with defined diameters, in order to achieve flow velocity of the liquid streams of more than 10 m/sec., and in that the liquid streams collide at a collision point in a space, wherein the resulting emulsion is discharged from the space through an outlet.

By the collision of the liquid streams with high flow velocities, in which a plate-shaped collision plate is formed in the collision point, a homogenous emulsion having an oil droplet size of less than 1 m is achieved due to the kinetic energy, which is accordingly very stable as well. No further energy input, such as shear forces, is required to that end.

Claims

1-13. (canceled)

14. A method for preparing emulsions, wherein in a first step, at least one pre-emulsion is prepared from at least two non-intermixable liquids, and then in a second step, in a microjet reactor, at least two liquid streams of the at least one pre-emulsion are pumped through separate nozzles with defined diameters, wherein the pressure of the liquid jets is between 5 and 500 bar, in order to achieve flow velocity of the liquid streams of more than 10 m/sec., and wherein the liquid streams collide at a collision point in a space, wherein the space is filled or pressurized with gas and the gas pressure in the space is 0.05 to 30 bar.

15. The method according to claim 14, wherein the diameter of the nozzles is identical or different, and is 10 to 5,000 m, preferably 50 to 3,000 m, and particularly preferably to 100 to 2,000 m.

16. The method according to claim 14, wherein the flow velocity of the liquid streams is identical or different and is more than 20 m/sec., preferably more than 50 m/sec., and particularly preferably to more than 100 m/sec.

17. The method according to claim 14, wherein the distance between the nozzles is less than 5 cm, preferably less than 3 cm and particularly preferably less than 1 cm.

18. The method according to claim 14, wherein the gas pressure in the space is 0.2 to 10 bar and preferably 0.5 to 5 bar.

19. The method according to claim 14, wherein the gas is heated or cooled before entering the space, in order to influence the temperature in the space.

20. The method according to claim 14, wherein a solvent is introduced into the space via another inlet.

21. The method according to claim 14, wherein a pressure of less than 100 bar, preferably less than 50 bar, and particularly preferably less than 20 bar prevails in the space during collision.

22. The method according to claim 14, wherein the liquid streams and/or the resulting emulsion are guided through a heat exchanger, in order to control the temperature of the liquid streams prior to the collision or the temperature of the emulsion after the collision, respectively.

23. The method according to claim 14, wherein the prepared emulsion is encapsulated in a further step.

24. The method according to claim 14, wherein in a further step, the prepared and possibly encapsulated emulsion is provided with a surface modification.

Description

EXAMPLE 1: EFFECTS OF GAS PRESSURE

[0038] The effect of the gas pressure was examined in that a liquid stream of oil and a liquid stream of water containing lecithin were made to collide under different gas pressures in a space, into which gas with different gas pressures was introduced through a gas inlet. The oil was pumped with a flow rate of 50 ml/min and the aqueous phase was pumped with a flow rate of 250 ml/min. The oil droplet size was determined by means of DLS. In all cases, an oil droplet size of less than 500 nm was achieved. The results show that the oil droplet size decreases with increasing gas pressure.

TABLE-US-00001 Pressure (bar) Oil droplet size (nm) 1 455 1.5 368 2 294 2.5 274 3 268

[0039] It can be concluded that the pressure acting on the system via the gas inlet has a direct influence on the oil droplet size.

EXAMPLE 2: EFFECT OF THE FLOW RATE

[0040] The effect of the flow rate was examined in that various flow rates were used for the oil phase and the water phase with a constant ratio of flow rates. For all experiments, a pressure of 2 bar was used in the space.

TABLE-US-00002 Oil flow rate (ml/min) Water flow rate (ml/min) Oil droplet size (nm) 10 50 596 20 100 427 30 150 348 50 250 294 100 500 257

[0041] The oil droplet size within the formed emulsion thus decreases with increasing flow rates.

EXAMPLE 3: DIAMETER OF THE OPENINGS

[0042] The influence of the diameter of the openings was determined in that different opening diameters were tested, while an oil flow rate of 50 ml/min and a water flow rate of 250 ml/min were used, and the gas pressure was 2 bar.

TABLE-US-00003 Opening diameter (m) Oil droplet size (nm) 200 294 300 318 400 567 500 785

[0043] The smaller the opening diameter, the smaller the oil droplet size within the formed emulsion.

EXAMPLE 4: NUMBER OF CYCLES

[0044] The oil and the water phases were pre-emulsified and pumped through the two inlets into a closed cycle in order to determine the influence of the number of cycles on the oil droplet size within the emulsion. A flow rate of 250 ml/min and a gas pressure of 2 bar prevailed in the space here.

TABLE-US-00004 Number of cycles Oil droplet size 1 650 2 540 3 420 4 355

[0045] The oil droplet size within the emulsion therefore also decreases with the number of cycles.

Encapsulation Via a Solvent/Non-Solvent Process: Example 5 to 8

EXAMPLE 5: COACERVATION

[0046] An essential oil to be encapsulated is emulsified, in the microjet reactor, at a flow rate of 67 g/min with an aqueous Na-caseinate solution (22.4 mg/ml) at a flow rate of 200 g/min. In the next step, this emulsion is processed with a flow rate of 200 g/min against an aqueous xanthan solution (0.25%) at 25 g/min. In this step, oppositely-charged side groups of the protein and of the polysaccharide mutually adsorb. Owing to the pH decrease to pH 4 by means of 10-% citric acid, this interaction is intensified, whereby microcapsules result. These microcapsules have a size of 50-100 m.

EXAMPLE 6: DRYING

[0047] An essential oil to be encapsulated is emulsified in the microjet reactor at a flow rate of 50 g/min into an aqueous whey protein isolate solution with a flow rate of 200 g/min. After adding 20% maltodextrin as a carrier material, the emulsion is spray-dried. A powder containing microencapsulated essential oil develops through the drying process.

EXAMPLE 7: MELT DISPERSION/MATRIX ENCAPSULATION

[0048] A fragrance (15-30%) to be encapsulated is dissolved in melted Compritol AO 888 at 85 C. This oil phase, at 68 ml/min, is emulsified into a 20 C. cold aqueous Tween 20 solution (0.5-1.5%) at 200 ml/min. Due to the rapid cooling of the fat, particle formation occurs directly with emulsion formation, and thus matrix encapsulation of the fragrance. The microcapsules are 5 m (0.5% Tween 20) or 2 m (1.5% Tween 20) on average.

EXAMPLE 8: MELT DISPERSION WITH MODIFIED SURFACE

[0049] A fragrance (15-30%) to be encapsulated is dissolved in melted Compritol AO 888 at 85 C. This oil phase, at 68 ml/min, is then emulsified into a 20 C. cold aqueous gum acacia solution (2.5%; 200 ml/min). Due to the rapid cooling of the fat, particle formation occurs directly after the emulsion formation.

[0050] A modification of the microcapsules is made in that the melt dispersion (200 ml/min) is processed, in die microjet reactor, against a 50 C. gelatin solution (2.5%; 150 g/min). By decreasing the pH-value to pH 4 through 10% citric acid, the ionic interactions are increased and gelatinized by cooling.

Relative Encapsulation: Examples 9 to 18

EXAMPLE 9

[0051] A hydrophilic polyalcohol (active substance) to be encapsulated is added (water phase) to an aqueous ammonia solution (1%) and processed, in the MJR reactor, against an emulsifying agent-containing (polyetheralkyl-polymethysiloxane) 1% encapsulation solution (TEOS) in isoparaffin (oil phase). With the solutions (50:50) having the same flow rate, a process pressure of 40 bar is set upstream the nozzles.

[0052] A stable emulsion is formed, on the phase interfaces of which the encapsulation material is formed due to hydrolysis of the precursors. The capsules can be separated by simple sedimentation or centrifugation and have a size between 5 and 10 m.

EXAMPLES 10 AND 11

[0053] The method used in 1 is applied to the encapsulating substances OTMS, PTMS.

[0054] At a constant flow rate, the obtained microcapsules have approximately the same characteristics at a reduced reaction time.

EXAMPLES 12, 13 AND 14

[0055] The method stated in 1 is applied to variable flow rates. By variation of the flow rate, ratios of the dispersing phase (active substance) to oil phase of 30:70, 40:60 and 60:40 can be realized.

[0056] The size of the obtained microcapsules increases with a growing proportion of the dispersing phase (active substance solution).

EXAMPLES 15 AND 16

[0057] The method stated in 1 is applied to a TEOS-containing encapsulation solution, with the modification that the concentration of the emulsifying agent used was reduced to 50% or 25% of the original concentration. The obtained microcapsules are larger than those achieved according to example 1.

EXAMPLE 17

[0058] The method stated in 1 is applied to another chemical encapsulation composition. A 20% solution of an aqueous substance to be encapsulated, the solution containing 10 meq NH2 of the encapsulating component HDMA, is processed in isoparaffin, in the MJR, against an emulsifying agent solution. The emulsion obtained this way is cured by adding 40 meq COCl a 20% trimesoyl chloride solution in Isopar. The obtained capsules have a size of between 2 and 30 m.

EXAMPLE 18

[0059] The method stated in example 17 is used, with the modification that curing of the capsules is effected in situ using a trimesoyl chloride solution by continuously introducing the solution into the reactor chamber via the 5.sup.th opening of the MJR reactor. The obtained capsules have approximately the same characteristics as were obtained according to example 9.

Oil-Dissolvable Active Ingredients: Examples 19 to 20

EXAMPLE 19

[0060] The method stated in Example 5 is applied to oil-dissolvable encapsulating substances. An oil-dissolvable active substance to be encapsulated is added into a 20%-solution of the encapsulating material (OTMS) in isoparaffin and mixed by stirring at room temperature for 5 minutes. In the MJR reactor, the solution obtained this way is processed at a process pressure of 40 bar, against an aqueous 2% emulsifying agent solution. A stable, homogenous emulsion results, and curing the capsules occurs by adding the catalyst dibutyltin laureate (0.5%), which capsules can be separated after curing by means of centrifugation or sedimentation.

EXAMPLE 20

[0061] The method stated in example 19 is applied, with the modification that curing of the capsules occurs by means of dibutyltin laureate in situ by continuously introducing the solution into the reactor chamber via the 5.sup.th opening of the MJR reactor. The obtained capsules have approximately the same characteristics as were obtained according to example 19.

Melt Dispersion/Matrix Encapsulation: Example 21

EXAMPLE 21

[0062] Step 1:

[0063] Fusing of a polymer (e.g. PEGs, waxes, fats, . . . )

[0064] By selecting the substance to be fused, either a hydrophilic or an oleophilic melt can be produced.

[0065] Step 2a:

[0066] Stirring the solid active substances into the melt (e.g. surfactants, peroxo compounds, enzymes, . . . )

[0067] Step 2b (as an Alternative to Step 2a):

[0068] Stirring the liquid active substance into the melt

[0069] Step 3a:

[0070] Transferring the modified melt in the MJR process using a cold non-solvent as a second liquid stream under precipitation of loaded polymeric microbeads.

[0071] Step 3b (as an Alternative to Step 3a):

[0072] Mixing the modified melt with a hot non-solvent (pre-emulsion). This pre-emulsion is introduced into the MJR on the left and on the right with a flow rate ratio of 1:1. Taking advantage of the cooling effect of the inert carrier gas, the loaded polymer is precipitated in microscale manner.

[0073] Step 3c (as an Alternative to Step 3a or Step 3b)

[0074] In order to reduce the melt viscosity, the modified melt is mixed with part of the heated non-solvent. The mixture is precipitated then with the cold remaining non-solvent in the MJR-process under precipitation of the polymeric beads.