MXPA98008569A - Dispersion of phases inmiscib - Google Patents

Abstract

A method for the preparation of an emulsion type mixture in which the discontinuous phase is introduced into a circulating continuous phase by passing through a membrane, which preferably is composed of a ceramic material or sinter metal

Description

DISPERSION OF IMMISSIBLE PHASES FIELD OF THE INVENTION This invention relates to an apparatus and a method for producing dispersions of two or more immiscible phases, for example in the manufacture of emulsions and encapsulated products where the properties of the droplets of the dispersed phase must be carefully controlled.

BACKGROUND OF THE INVENTION The production of oil-in-water and water-in-oil emulsions and other multiphase mixtures is of significant global economic importance, but the manufacturing method can be problematic, especially as it is adapted from the laboratory to the pilot and production levels. . For example, emulsions are often made in batches and there are variations in them, so the process can be irreproducible in large-scale manufacturing. For example, most of the emulsion manufacturing methods that exist are based on the establishment of turbulent flow in a fluid mixing regime, consisting of two immiscible liquids contained in a single manufacturing container. Due to turbulent eddies produced by agitation P1611 / 98MX vigorous, one of the phases is broken into drops (the discontinuous phase) that are suspended in the other phase (continuous). The size and the size distribution of these drops are of critical importance, since they determine the stability of the emulsion against coalescence and its suitability for a particular use. For a specific pair of phases processed by this existing method, the size of the drop is determined first by the size of the turbulent eddies and by the time of exposure to them. In the literature (alstra, Encyclopaedia of Emulsion Technology, Vol.l, 1983, Belcher (Ed., Deker, New York) relations have been proposed that correlate the size of the drop with the input of energy (through agitation) by volume unit The value of the input energy depends on the surface tension of the liquids, their density and the power of a specific geometry agitator.The input energy typically can vary from 104 watts per cubic meter (for a paddle agitator) at 1012 watts per cubic meter (for a high pressure homogenizer) The usual problem is that such processes are inefficient because neither turbulence can be consistently controlled or generated through the volume of the liquid in the large manufacturing containers , nor the behavior of any pair of immiscible phases can P1611 / 98MX predicted on a large scale based on laboratory experiments. The consequence is that this energy is used inefficiently and, most importantly, that it is not possible to control with confidence the size or the distribution of the size of the drop. Alternative methods have been proposed, based for example on the use of electrostatic or ultrasonic nozzles for the formation of gout; however, the quality of the resulting product, the cost and the scalability of these methods are not attractive. Recently, several methods have been proposed where a membrane is used to facilitate the mixing of the two phases. Japanese Patent Application No. 2-214537 (published on August 27, 1990) proposes a method for the preparation of emulsions in which the aqueous phase is passed under pressure, through the pores of a membrane, towards a An oil phase containing a surfactant, the membrane is subjected to ultrasonic radiation during the process. Nakashima et.al., Key Engineering Materials, 1991, Vol. 61-62, p.513-516, discloses a method for preparing emulsions, wherein the oil phase is passed through a membrane to an aqueous phase containing an surfactant, one condition is that the oil phase does not wet the membrane. Later works by Nakashima et al. They are described in several patent specifications, P1611 / 98MX specifically EP 546,174 Al, US 4,657,875 and US 5,326,484. In these, the membrane is made of glass and its pores are of uniform size. In more specialized technology, the specification of the European patent N °. 452, 140 Al discloses a method for the manufacture of emulsions by passing from one phase to the other through a membrane, particularly in the field of food processing in dispersion. WO Specification No. 87/04924 is directed to the manufacture of liposomes and includes the use of a commercially available asymmetric ceramic filter.

SUMMARY OF THE INVENTION According to the present invention, a method for the preparation of an emulsion-type mixture is established, wherein the discontinuous phase is introduced to a circulating continuous phase by passing through a membrane, which is characterized at least by one of the following features: (a) is composed of a ceramic material or sintered metal; (b) is formed by numerous segments which may be identical or different from each other; (c) at least one segment is tubular in shape and P1611 / 98 X diameter diverging along the length of the tube. According to a further feature of the invention there is provided an apparatus designed to enable the method of the invention to be carried out, said apparatus comprising a membrane as defined above together with the means for supplying a circulating continuous phase, a discontinuous phase and a pressure source for passing the discontinuous phase through the membrane. The factors that determine the size of the drops in the discontinuous phase and the size distribution of said drops are: (i) the shape, the surface chemistry and the size and distribution of the pore size of the membrane; (ii) the flow rate of the continuous phase through the membrane; (iii) the pressure under which the discontinuous phase is passed through the membrane; (iv) the individual temperatures of the two phases; and (v) the interfacial tensions, densities and viscosities of the phases. The membrane itself is preferably made of a ceramic material and, more particularly, it is substantially preferable that it be tubular in which the pores pass radially to P1611 / 98MX through the tube material. The size and the size distribution of the pores of the membrane will be determined by the type of emulsion desired. For example, if it is desired that the drops of the oil phase have 1 μm in diameter, a pore size of the order of 0.35 μm will be required. The surface chemistry of the membrane can be adapted to provide various degrees of wettability. When the membrane is made of sintered metal, it should preferably have a surface finish of laminate. The method and apparatus of the invention can be adapted to produce a single-phase emulsion or an emulsion containing numerous discontinuous phases and can operate in both batch and continuous production. When a batch process is desired, the membrane may be in the form of a diverging tube. The continuous aqueous phase is circulated and recirculated through the interior of the tube and the discontinuous oil phase is passed through the wall of the tubular membrane to the continuous phase. The tube is divergent to keep the tangential force constant along the length of the surface of the membrane, as the total volume and viscosity of the emulsion increase, more oil phase is added to the aqueous phase during the passage to along the P1611 / 98MX tube. However, this divergence is not absolutely essential for the operation of the invention. To ensure that there is uniformity of the drop size along the tube, the pore structure of the membrane can be varied both in terms of the individual pore area and in the number of pores per unit area of the membrane. The circulation of the aqueous phase is stopped when the volume of the oil phase in the emulsion has reached the desired level. When a continuous process is desired, the continuous phase is recirculated via storage tank from which the desired emulsion stops draining when the volume of the oil phase has reached the desired level. The membrane may consist of a single tubular structure, as described above, or of numerous tubular structures arranged in series to form a segmented tubular structure. The individual segments of the tubular membrane may be adapted to allow diversity of different droplet sizes or droplet size distributions of the same oil phase or to provide different oil phase diversity, with same or different droplet sizes or distributions. The surface chemistry and geometry of the membrane itself and the pressure at which the oil phase is passed through the membrane can P1S11 / 98MX vary as desired for each of the individual segments. It is also important that the temperatures of the different oil phases and of course the continuous phase, can be adjusted individually to optimize the operation of the invention. According to a further particular feature of the invention, a method of preparing an emulsion type mixture is established, wherein the discontinuous phase consists of an encapsulated substance, which comprises the use of a segmented membrane of the type described above, wherein the The first segment distributes a discontinuous phase to a continuous phase and another segment distributes another discontinuous phase which covers the first discontinuous phase. The initial emulsion is generally prepared as described above. The encapsulation process can then be carried out, for example, by passing the initial emulsion through a conical tube to a narrow piercing tubular membrane incorporating a flow divider along its axes, to reduce the effective area of flow between the divider and the surface of the membrane. Another oil phase is introduced into the narrow piercing tubular membrane, generally by the means described above, and then a coating is formed on the P1611 / 98MX drops of the initial oil phase. It should be understood that the surface properties of the other membrane are important for the control of the oleophilicity of the other oil phase and thus improve the coating of the initial oil phase. According to a further particularity of the invention, a method is established for controlling the start of an emulsification process as described above, which comprises the use of on-line measurements of the size and distribution of the droplet size of the discontinuous phase initially formed, as feedback signals for the control of the transverse flow rate of the continuous phase and thus ensure that the size and desired size distribution of the drops of the final discontinuous phase are obtained. Online measurements can be obtained using laser microscopy, conductivity measurements and / or other suitable measurement methods. These measurements can be used separately to provide assurance of the quality of the desired product.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be illustrated with reference to the following drawings which are only examples thereof and are not intended to be limiting of its scope: P1611 / 98MX Figures 1 to 8 illustrate a first exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a schematic diagram of a unimodular transverse flow membrane unit which comprises: (a) a container (2) containing the aqueous phase and which is adapted to supply the recirculation of that phase; (b) a container (11) containing the oil phase; (c) a transverse flow membrane unit (10) through which the oil phase can pass into the aqueous phase; and (d) a container for the final product (18). Both containers (2) and (11) have heating means (1) and (12), respectively, and the container (18) has cooling means (19). The container (11) also has filling means (8) and a pressure source (9). The various pumps, manometers and valves for interconnecting the containers will be described later in the description of the process for the operation. The membrane unit (10) is shown in more detail in Figure 1 (a). The cylindrical membrane itself P1611 / 98MX (25) itself is supported by a body (usually made of stainless steel) (22) and by an additional concentric body (usually made of stainless steel) (26), separated from the body (22) by seals (23) and adjustable by means of clamps (29), it has a chamber (24) for the oil phase. The means of entry also have a purge for gases (21), for the oil phase (27) and for the aqueous phase (28). In operation, the container (2) is filled with the aqueous phase to an appropriate level through the valve (4), the valve (17), the sampling valve (15) are closed. The container (11) is filled to an appropriate level, with the oil phase suitably emulsified, through the funnel and valve (8), the purge and pressure valves (9) are opened and the valve (13) is closed . The contents of both containers are heated to a suitable temperature by means of the heating bands (1) and (12). Then the aqueous phase is flowed through the apparatus by operation of the pump (16) and the valve (4) as shown by the flow meter (3) and the pressure gauges (5) and (14). In the container (11) the oil phase is brought to a suitable pressure by means of the pressure valve (9), initially the air is purged from the chamber (24) having the valves (6) and (13) open, the valve (8) P1611 / 98MX closed and the distension valve (7) fixed at the safety level. When all the air is purged, the valves (6) and (13) are closed and the oil pressure is maintained and maintained at an appropriate level by means of the valve (9). The emulsification process is initiated by opening the valve (13), the oil phase is pressurized to the aqueous phase through the inlet (27) and through the membrane (25) through the membrane unit (10). The process is continued until the volume of oil in the emulsion reaches the desired level. This can be determined by noting that the volume of the oil phase remains in the container (11) and by the samples of the emulsion through the sampling valve (15). Small variations in the flow rate of the aqueous phase can be controlled by the valve (4). The process is completed by closing the valve (13) and disconnecting the pressure valve (9). The finished product is transferred to the container (18) by closing the valve (4) and opening the valve (17), and then it can be cooled to an appropriate temperature using a jacket (19) and removed from the system through the valve (20) . Figure 2 shows a sequence of photographs taken with a high-speed video camera, of the detachment of an oily drop from a pore of the membrane.

P1611 / 98 X The data shown is for a thick pore of 98 μm in diameter and a drip pressure of 2 psi. The photograph of double stripes represents the final detachment of the drop from the pore; it can be seen that the increase in the transverse flow velocity of the aqueous phase from 0.19 m / s to 0.40 m / s decreases the time of formation of the drop from 2380 to 420 milliseconds. Figure 3 shows an electronic micrograph of the surface of a ceramic membrane with a wide range of pore sizes. Figure 4 graphically shows the relationship between the pore size distribution, the transverse flow velocity of the aqueous phase and the predicted distribution of the oil drop size. The droplet size distribution can be controlled by varying the pore size distribution as well as the cross flow rate. Figure 5 shows in graphical form the effect of the increase in the transverse flow velocity of the aqueous phase on: (a) size of the drop; (b) number of oily drops produced per pore in unit of time; (c) escape velocity of oil droplets from the pore (determined using a high-quality video camera) P1611 / 98 X speed); and (d) Reynolds number based on the tube diameter of the membrane module. All data were obtained using a thick pore size of 98 μm in diameter and. a pressure drop of 2 psi. It can be seen that increasing the cross-flow velocity reduces the size of the oil droplets but increases the production rate thereof. Figure 6 shows in isometric diagrammatic form the relationship between oil drop size and: (a) the transverse flow rate of the aqueous phase; Y (b) the drip pressure across the membrane. Figure 7 shows in graphical form an example of droplet shedding per area (m2) of membrane.

This example is taken from a batch process using a thick membrane with a narrow pore size distribution. Figure 8 shows a schematic diagram of a segmented tubular membrane (corresponding to point 10 in Figure 1) which admits either of the two droplet sizes of the same oil phase (in which case the same type of oil phase will be contained in Chambers 1 and 2 and membranes 3 and 4 will differ from one another) or for two different oil phases (in which case two oil phases Different P1611 / 98MX will be contained in cameras 1 and 2 and membranes 3 and 4 may be the same or different). The system can be expanded by the use of additional membrane segments to supply more than two different oil phases and / or oil drop sizes. In a second modality, exemplified in Figures 11 to 16, Figure 11 shows a schematic diagram of a single-module cross-flow membrane unit, similar to that shown in Figure 1, which is adapted to provide continuous emulsion production to room temperature. This comprises a continuous phase (aqueous) tank equipped with an agitator, a discontinuous phase (oil) tank, a washing tank, a continuous phase circulation pump, a manometer, a membrane module, all labeled, and the valves numbered from 1 to 6, whose functions are described below. Figure 11 (a) shows the membrane module in diagrammatic form; This is similar to the one described in Figure 1 (a) and is appropriately labeled. The ceramic element is 600 mm long and has a 5 mm internal diameter. The inner surface can be coated to produce an average pore size of a range above 0.1 and typically 0.2 μm. In operation, the tanks of the two phases are P1611 / 98MX fill with the appropriate fluids, the membrane is saturated with aqueous phase and with all the closed valves the pump and the agitator are connected (the last one slow enough to avoid whirl movement). By adjusting the pump, the flow rate of the aqueous phase through the membrane is reduced to the desired speed. The valves 3 and 6 are then opened and air is left inside the system to produce the desired pressure in the oil phase. Opening the valve 2 then starts the emulsification process. The droplet size distribution in the aqueous phase tank was monitored until the desired emulsion formed, at which point the process was stopped by closing all the valves, releasing the air pressure and stopping the pump and agitator. The finished product was released from the aqueous phase tank and the system was washed before the next operation. In a third embodiment, exemplified in Figures 21 to 27, Figure 21 shows a schematic diagram of a unimodular transverse flow membrane unit which comprises: (a) a container (2) containing the aqueous phase and which is adapted to provide the recirculation of that phase; P1611 / 98MX (b) a container (43) containing the oil phase; (c) a transverse flow membrane unit (14) through which the oil phase can pass to the aqueous phase; and (d) a container for the final product (31). Both containers (2) and (43) have heating means (4) and (32) respectively and the container (31) has cooling means (25). The container (43) has a removable lid and also has a pressure source (39). The various pumps, manometers and valves for interconnecting the containers will be described later in the description of the process for the operation. The membrane unit (14) is shown in more detail in Figure 21 (a). The cylindrical membrane itself (46) is supported by a body (usually stainless steel) (52) and by an additional concentric body (usually stainless steel) (45), separated from (52) by seals (49) and Adjustable by clamps (44,48), it has a chamber (50) for the oil phase. The input means also have a purge for gases (51), for the oil phase (47) and for the aqueous phase (53). In operation, the container (2) is filled to an appropriate level with the aqueous phase through the valve P1611 / 98MX (20). The container (43) is filled to an appropriate level with the suitably emulsified oil phase through the removable lid. The contents of both containers are heated to a suitable temperature by means of the heating bands (4) and (32). Then the aqueous phase is flowed through the apparatus by operation of the pump (19) and regulated by the valve (7) as shown by the flow meter (3) and the pressure gauges (12) and (17). In the container (43) the oil phase is brought to a suitable pressure by means of the pressure valve (39) and the air regulator (38), initially the air is purged from the chamber (50) having the valves open ( 47) and (51), and the distension valve is fixed (35) at the security level. When all the air is purged, the valves (47) and (51) are closed and the oil pressure is maintained and maintained at an appropriate level by means of the valve (39) and the regulator (38). The emulsification process is initiated by opening the valves (40, 41), the oil phase is pressurized to the aqueous phase through the inlet (47) and through the membrane (46) through the membrane unit (14). ). The process is continued until the volume of oil in the emulsion reaches the desired level. This can be determined by noting that the volume of the oil phase remains in the container (43) and by the samples of the P1611 / 98 X emulsion through the sampling valve (13). Small variations in the flow rate of the aqueous phase can be controlled by the valve (7) or by the lobe pump (19). The process is completed by closing the valves (40, 41) and disconnecting the pressure valve (39) thus releasing the drip pressure. The finished product is transferred to the container (31) by connecting the valve (22) and can be cooled to an appropriate temperature using a jacket (25) and removed from the system through the valve (30). Figure 22 shows an accurate representation of the drops growing in a pore, derived from observations made with a high-speed camera, at specific times. The results are shown for a single thick pore of 98 microns in diameter and a drip pressure of 2 psi. It can be seen that the increase in the transverse flow rate of the aqueous phase from 0.19 m / s to 0.40 m / s decreases the time of formation of the drop from 2380 to 420 milliseconds. Figure 23 shows: (a) an electron micrograph of the surface of a ceramic membrane; (b) image analysis that reveals the apparent surface area of the pores; and (c) a cross section of the membrane showing a P1611 / 98MX example of the thinnest coating layer coating a thick substrate. Figure 24 graphically shows the effect of the increase in the transverse flow velocity of the aqueous phase on: (a) drop size; (b) number of oily drops produced per pore in unit of time; (c) escape velocity of oily drops from the pore (determined using a high-speed video camera); and (d) Reynolds number based on the tube diameter of the membrane module. All data were obtained using a coarse pore size of 98 μm in diameter and a drip pressure of 2 psi. It can be seen that the increase in the transverse flow rate of the aqueous phase reduces the size of the oil droplets but increases the number thereof. Figure 6 shows in isometric diagrammatic form the relationship between the oil droplet size, the transverse flow rate of the aqueous phase and the drip pressure across the membrane. Figure 26 shows a schematic diagram of a segmented tubular membrane (corresponding to the P1611 / 98MX 14 in Figure 1) which admits either of the two droplet sizes of the same oil phase (in which case the same type of oil phase will be contained in chambers 1 and 2 and membranes 3 and 4 will differ one of another) or for two different oil phases (in which case two different oil phases will be contained in the chambers 1 and 2 and the membranes 3 and 4 can be the same or different). The system can be expanded by the use of additional membrane segments to supply more than two different oil phases and / or oil drop sizes. Figure 27 shows the distribution of droplet size produced using a double assembled membrane (as described in figure 26) having average pore diameters of 0.5 microns and 4.0 microns, and operated at 40 psi and 10 psi respectively. In the example presented below, all compositions% are weight / weight.

Example 1 An aqueous phase was prepared by adding sorbitol mono oleate ("Span" 80) (2.5%) to a stirring solution of polyoxyethylene sorbitan mono oleate ("Tween" 20) (2.5%) and ("Nipastat" sodium) (0.3%) in water (64.7%) and the mixture was charged to the aqueous phase tank of an apparatus such as that described in Figure 11. In the tank of P1S11 / 98MX oil phase was loaded with mineral oil (30.0%) and the emulsification process was carried out for 4.5 hours with an initial transverse flow rate of 5.09 m / sec, to produce a 30% oil-in-water emulsion. The pore size distribution and the droplet size distribution are shown in Figure 12; the average drop size was 2.03 μm and the pore size was 0.41 μm, giving a ratio of 4.95. In general terms the droplet size distribution can be described in terms of the distribution coefficient e defined by the equation: e = (D90 - D10) / D50 where D90, D50 and D10 are particle sizes obtained when the cumulative frequencies of the emulsion determined in a Malvern Instruments Mastersizer team are 90%, 50% and 10% respectively. For a perfect monodisperse system, e is zero. In the present example, the emulsions produced give a value of no more than 0.6, and in the best case not greater than 0.3. The distribution of the pore sizes in the membrane can be defined by the same with a value no greater than 0.6 and that none of the pores have a size greater than 150% of the average pore size. The size and distribution of the pore size remained unchanged for several weeks, although there was somewhat premature phase separation. Figure 12 (a) shows a microphotograph of the product (magnification x P1611 / 98 X 400); The streaks in the image are due to marks on the camera lenses.

Example 2 An aqueous phase consisting of a solution of triethanolamine (3.0%) and sodium "Nipastat" (0.3%) in water (66.7%) was charged to an aqueous phase tank of an apparatus as described in Figure 11. A solution of isothermal acid (3.0%) in mineral oil (27.0%) was charged to the oil phase tank and the emulsification process was carried out for 6 hours with four different flow rates cross. Figure 13 (a) shows the pore size distribution (identical to the one shown in Figure 12) and Figure 13 (b) shows the drop size distribution for each of the four speeds. Transverse flow rates are given as a range, because as the concentration of oil in the emulsion increases, it becomes more viscous (as indicated by the Reynolds number reduction, which is a function of velocity by density divided by viscosity). In practice, the speed drops by about 10% towards the end of the process. In the graph of the droplet size distribution the peak corresponding to the highest transverse flow velocity originates from the inability of the measuring equipment P1611 / 98MX to handle very small drop sizes. Figure 14 shows the relationship between the ial transverse flow velocity and the average droplet size. With the increase in speed there is an almost linear decrease in the average drop size. Figure 15 shows the relationship between the progression of the process time and: (a) concentration of oil in the emulsion (30% towards the end of the process); (b) average drop size; (c) transverse flow velocity through the membrane; and (d) viscosity of the emulsion. The concentration of oil (a) and the viscosity (d) both as expected increase with time and the cross-flow velocity (c) decays as explained above. In practice the average drop size (b) decreases slightly with time. Figure 16 shows a microphotograph of the product of Example 2 when the highest exemplified flow rate (5.09 m / sec.) Is used. As shown in the Figure 12 (a). The drops are smaller than those obtained from Example 1 P1611 / 98MX Example 3 This example describes by way of illustration the manufacture of a cosmetic type emulsion at room temperature, and the effect of the transverse flow velocity on the drops thus produced. An aqueous phase consisting of a solution of triethanolamine (3.0%) and sodium "Nipastat" (0.3%, a preservative) in water (66.7%) was charged to a harassing phase tank (Figure 21, point 2) and a solution Isosteary acid (3.0%) in mineral oil (27.0%) was charged to the oil phase tank (Figure 21, point 43). Four emulsification processes were carried out at four different cross-flow rates in different batch experiments. The results are shown in Figure 28. Curve (1) shows the pore size distribution. The curves (2), (3), (4) and (5) shows the distribution of the drop size of the product, determined by means of the Malvern Mastersizer equipment, for each of the cross flow rates 1.12, 2.49, 4.34 and 5.09 m / s respectively. Figure 29 shows a typical microphotograph of a product manufactured by this process.

Example 4 This example demonstrates how the P1611 / 98MX control of the size of the drop by the selection of the properties of the membrane, in particular by the selection of the pore size. An aqueous phase was prepared by adding "Dobanol" (2.96%) and formalin (0.04%) to a well-stirred solution of sorbitol (36%) in water (36%) and loading into an aqueous phase tank (Figure 21, point 2) . Mineral oil (25%) was charged to the oil phase tank (Figure 21, point 43) and two emulsification processes were carried out, one using a ceramic tubular membrane (Figure 21 (a), point 46) of pore size nominal 0.2 microns and the other using a tubular membrane with a nominal pore size of 0.5 microns. The results are shown in Figure 30 in which the Pl and P2 curves show the pore size distribution and the DI and D2 curves show the droplet size distribution determined using a Malvern Mastersizer equipment, respectively.

Example 5 The process described in Example 4 was repeated (using a ceramic tubular membrane of nominal pore size of 0.5 microns) except that when the desired oil concentration was reached (after 100 minutes) more aqueous phase was added continuously, the emulsion product was continuously removed, the P1611 / 98 X flow rates were matched to the flow rate of the oil, so that the concentration of the emulsion in the aqueous phase tank was maintained at that of the final product. The measurements of the concentration of the emulsion, the production rate and the particle size as a function of time were made using a laser microscope (Type FRBM, Lasentec Corp.). The results are shown in Figure 31; the concentration of the emulsion in Figure 31 (a), the flow velocity of the oil in Figure 31 (b), the count of the drop size number in Figure 31 (c), and the size of the drop Figure 31 (d). Figure 32 shows the pore size distribution of the membrane (curve 1) and the droplet size distribution (curve 2). From these results it is clear that the use of online instrumentation associated with computers for control allows the continuous production of an emulsion to be achieved.

Example 6 This example demonstrates the production of a cosmetic emulsion at high temperature and low tangential force. An aqueous phase was prepared by slowly adding "Carbomer" 934 (0.1%) in well stirred water (88.25%) P1 &11 / 98MX maintained at 80 ° C and then slowly adding triethanolamine (1.0%). The solution was loaded into the aqueous phase tank and maintained at 80 ° C by the use of the heating band (Figure 21, item 4). An oil phase was prepared by heating a mixture of petroleum jelly (6.5%), mineral oil (2.0%), stearic acid (1.5%) glyceryl monostearate (0.4%) and isopropyl isostearate (0.25%) at 80 ° C and it was charged in the oil phase tank, it was kept at 80 ° C using the heating band (Figure 21, point 32). The emulsification process was carried out at a transverse flow velocity of 0.5 m / s. Figure 33 (a) shows a cryogenic micrograph of the product obtained by the above process, while Figure 33 (b) shows a similar micrograph of an emulsion prepared by a conventional high tangential force process. It can be seen that the laminar phase of stearate seems to break in the conventional high tangential force process but is completely intact in the present example, the dispersed oil droplets are otherwise identical. The product of the present example has different application properties from the user's perspective.

P1611 / 98MX Example 7 An aqueous phase in the gel form was prepared by adding sodium chloride (2.0%) to a solution of etherified sodium lauryl sulfate (40%), cocoamidopropylbetaine (10%), cocodiethanolamide (2.0%) and preservative ( 0.2%) in water (35.8%) and loaded in an aqueous phase tank. In the oil phase tank silicone oil was charged and the emulsification process was carried out using a stainless steel membrane (Figure 21, point 46, average pore size 40 microns) until the concentration of silicone oil in the product was 10%. The distribution of the droplet size of the product, which can be used as a bath gel, is shown in Figure 34. It can be seen that the size of the drop is comparable to the pore size of the membrane.

P1611 / 98MX

Claims (9)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A method for the preparation of an emulsion type mixture, wherein a discontinuous phase it is introduced into a circulating continuous phase by the passage through a membrane, which is characterized by at least one of the following particularities: (a) it is composed of a ceramic material or sintered metal; (b) is formed by numerous segments which may be identical or different from each other; (c) at least one segment is tubular in shape and divergent in diameter along the length of the tube. A method as claimed in Claim 1, wherein the membrane is composed of a ceramic material and is substantially tubular in shape and the pores pass radially through the material of the tube. 3. An apparatus designed to allow the method according to Claim 1 to be carried out, said apparatus comprising a membrane as defined in Claim 1 together with the means for supplying a P1611 / 98MX continuous circulating phase, a discontinuous phase and a pressure source to pass the discontinuous phase through the membrane. 4. An apparatus as claimed in Claim 3 wherein the membrane is composed of a ceramic material and is substantially tubular in shape and the pores pass radially through the tube material. A method of preparing an emulsion-type mixture wherein the discontinuous phase consists of an encapsulated substance, which comprises the use of a segmented membrane of the type described in Claim 1, wherein a first segment distributes a discontinuous phase in a continuous phase and another segment distributes another discontinuous phase which covers the first discontinuous phase. 6. A method as claimed in any of Claims 1 to 5 wherein the temperatures of the individual phases can be adjusted individually. 7. A method as claimed in the
1. Claim 1, wherein the membrane is composed of stainless steel and wherein the emulsion produced is in the gel form. 8. A method to control the start of an emulsification process as claimed in the P1611 / 98MX Claim 1, which comprises the use of on-line measurements of the size and droplet size distribution of the discontinuous phase initially formed as feedback signals for the control of the transverse flow rate of the continuous phase and thus ensure that the desired size and size distribution of the drops of the final discontinuous phase are obtained. 9. A method as claimed in claim 8 wherein the online measurements are made by the use of a laser microscope. P1611 / 98MX