EP1781402B1 - Device for gentle mechanical generation of finely dispersed micro-/nano-emulsions with narrow particle size distribution - Google Patents

Abstract

This invention relates to a method for the mechanically protective production of finely dispersed micro-/nanoemulsions with narrow droplet size distribution, whereby drops are produced on the surface of a membrane or of a filter fabric, and the drops are detached from the membrane or filter fabric surface by motion of the membrane or of the filter fabric in a first immiscible liquid phase in which pronounced stretching flow components in particular, besides shear flow components, bring about the detachment of the drops formed on the membrane surface especially efficiently and protectively. The invention also relates to a device for implementing the method according to the invention with a membrane or filter unit that is positioned to move, in particular to be able to rotate, in a housing with a gap that may be eccentric toward the inner wall of the housing and/or provided with flow baffles that produce stretching flow components.

Description

genus

The invention relates to a device for mechanically gentle production of finely dispersed micro / nano-emulsions with a narrow droplet size distribution.

State of the art

The production of finely dispersed emulsions is considered an important development goal for the food, pharmaceutical, cosmetics and chemical industries. The reason for this is the possibility of having such emulsions with sufficient smallness of the disperse droplets entmischungsstabil to use and the extremely large inner interface for the adsorption of functional ingredients (eg., Active ingredients, flavors, dyes, etc.). Furthermore, the disperse drops allow the construction of particle networks to which have a specific influence on the rheological properties of such emulsions.

Membrane emulsification processes are a new area for machine / apparatus manufacturers. Traditionally, rotor / stator dispersing systems and high-pressure homogenizers are used for fine emulsification. In these apparatus, the droplet is dispersed under extremely high mechanical stress of the disperse as well as the continuous phase. The present since about five years Membrane emulsification are very gentle from the conventional methods mentioned above, since the finely dispersed emulsion droplets are not produced by the tearing of larger drops, but these are formed and detached in their final size at the outlet openings of the membrane pores.

In previously existing continuous membrane processes, the membrane is overflowed by the continuous emulsion fluid phase in the form of a pure shear flow. The shear stresses acting on the droplets, which detach them from the membrane, are not very or not at all efficient, especially with higher drop viscosities, with regard to the detachment of small droplets or their further dispersion (division). This poses a significant disadvantage with regard to the optimized adjustability of small droplet sizes and narrow droplet size distribution width in the industrial production of Emulsion systems usually within narrow limits specified throughput.

By the WO 01/45830-A1 is a cup-like structure previously known in which coaxially a tube with radially extending holes or holes dips, which is driven by a motor. Through the pot-shaped housing one phase and through the tubular sieve the other phase is introduced and to be mixed by centrifugal force with the first in the cup-shaped housing phase to form an emulsion. The finished mixture leaves through a radially disposed channel the cup-shaped housing.

From the EP 1 262 225 A2 a device for producing emulsions with a housing with inlet and outlet opening for a continuous phase of a first liquid medium is previously known, with a rotatably driven in the housing arranged shaft, formed on or in a supply channel for a disperse phase of a second liquid medium is. The device has a plurality of opposite the outer diameter of the shaft considerably enlarged in diameter disk-shaped, hollow membrane body, which are formed as membrane discs and which are arranged in the longitudinal axis of the driving shaft with gap spacing and with gap distance between these membrane bodies arranged ridge-shaped housing parts. The shaft is concentric with the membrane discs, with the feed channel over the shaft the interior of the individual membrane body is connected to allow the supply of the disperse phase via the supply channel in the disk-shaped membrane body. The continuous phase is introduced radially into the gap distance between the radial housing webs and the various membrane disks and coaxially exits the housing after it has peeled from the membrane discs emerging droplets of the disperse phase and mixed with these to form an emulsion.

From the US 2003/0024878 A1 There is also previously known a device in which a continuous phase is pumped through a tubular housing and a second medium is pumped into the annulus surrounding the tube for the first phase. The membrane curves are used to mix the two phases, with the emulsion at the end of the tubular housing leaving it.

task

The invention has for its object to provide a device for mechanically gentle production of finely dispersed micro / nano-emulsions with narrow droplet size distribution.

solution

This object is achieved by the reproduced in claim 1 features.

Some advantages

In the apparatus according to the invention the gentle detachment of smaller drops and their more efficient further dispersion after detachment is possible due to a shear flow superimposed Dehnströmungsanteile on the rotating membrane surface, as is the case with realization of pure shear flows of the case.

Emulsion droplets are produced in the device according to the invention on the surface of a pore-permeated membrane or a filter fabric by pressing a first fluid phase through these pores and removing the droplets from the membrane surface by rotating them in a second with the first immiscible fluid phase takes place. The detachment of the fluid droplets from the membrane surface is effected by tangential and normal stresses acting on them, supported by additional centrifugal forces. The preferred use of membranes with defined pore spacing compared to pore diameter x (≥ 2x) is additionally conducive to the generation of a narrow droplet size distribution in the emulsion produced. In comparison to conventional membrane emulsification processes with fixed or rotating membranes, which are overflowed by pure shear flows, the membrane overflow according to the invention, which is realized with additionally efficient expansion flow fractions, permits the production of significantly smaller droplet diameters with a comparable pore diameter. Compared to conventional emulsification processes by means of high-pressure homogenizers or rotating rotor / stator dispersing systems, the emulsion droplet production according to the invention offers the advantage of significantly reduced mechanical stress at comparable diameters of the droplets produced. This has advantages in terms of preserving native properties of functional content components, such as proteins in the droplets or at their interfaces.

Moreover, the device according to the invention allows the simple modification and adaptation of the expansion flow overflow characteristic of the membrane according to the invention with regard to the proportion of the expansion flow to the total flow by varying the eccentricity of the rotating diaphragm cylinder and / or easily exchanged flow installations.

The inventive device is very compact, since the membrane body can be arranged in the housing with a narrow gap distance to the inner wall.

Other inventive embodiments

Further inventive embodiments are described in claims 2 to 23 .

Fig. 1

eine erfindungsgemäße Vorrichtung im axialen Längsschnitt, wobei die geschnittenen Wände allerdings zur Vereinfachung nicht schraffiert dargestellt sind;

Fig. 2

einen orthogonal zur Längsachse der aus Fig. 1 ersichtlichen Vorrichtung geführten Querschnitt;

Fig. 3

ebenfalls einen orthogonalen Querschnitt zur Längsachse einer Vorrichtung gemäß der Erfindung, bei einer weiteren Ausführungsform mit Strömungseinbauten;

Fig. 4

eine graphische Darstellung der Tropfenanzahldichteverteilung (q₀-Verteilung), die bei 1000 bis 8000 Umdrehungen pro Minute des Filter- oder Membrankörpers aus Wassertropfen in Sonnenblumenöl aufgenommen wurde; und

Fig. 5

eine graphische Darstellung der Tropfen-Anzahlsummenverteilungen (Q₀-Verteilung), die bei 1000 bis 8000 Umdrehungen pro Minute des Filter- oder Membrankörpers aus Wassertropfen in Sonnenblumenöl aufgenommen wurden (sogenannte Q₀(x) - Verteilungen) mit Eintrag der charakteristischen Tropfengrößen x_90,0 und x_10,0, deren Verhältnis (x_90,0/x_10,0) als geeignetes Maß für die Tropfengrößenverteilungsbreite herangezogen wird, und zwar zentrische Anordnung (Z) und exzentrische Anordnung (EZ).

Mit dem Bezugszeichen 1 ist eine kontinuierliche Fluidphase bezeichnet, die aus einem geeigneten Vorratsbehälter (nicht dargestellt) unter Pumpleistung einem Anschluss 2 und über diesen einem Spalt 3 zugeführt wird.Moreover, further advantages result from the following description of the drawing, in which the invention is illustrated, for example. Show it:

Fig. 1

a device according to the invention in axial longitudinal section, wherein the cut walls are shown, however, not hatched for simplicity;

Fig. 2

an orthogonal to the longitudinal axis of the Fig. 1 apparent device guided cross section;

Fig. 3

also an orthogonal cross-section to the longitudinal axis of a device according to the invention, in another embodiment with flow baffles;

Fig. 4

a plot of drop number density distribution (q ₀ distribution) taken at 1000 to 8000 revolutions per minute of the filter or membrane body from water droplets in sunflower oil; and

Fig. 5

a graphical representation of the droplet number distributions (Q ₀ distribution), which were recorded at 1000 to 8000 revolutions per minute of the filter or membrane body of water droplets in sunflower oil (so-called Q ₀ (x) - distributions) with entry of the characteristic drop sizes x _{90 , 0} and x _10.0, whose ratio (x _90.0 / x _10.0 ) is used as a suitable measure of the droplet size distribution width, centric arrangement (Z) and eccentric arrangement (EZ).

The reference numeral 1 denotes a continuous fluid phase, which is supplied from a suitable reservoir (not shown) under pump power to a port 2 and via this a gap 3.

4 denotes disperse drops and 5 denotes a membrane or filter fabric body, while 6 represents a cylinder body designed as a membrane cylinder.

With 7 as a hollow shaft formed rotary shaft is designated, which has an inner, centrally arranged bore 8. The shaft 7 is sealed by a dynamic mechanical seal 9.

The bore 8 opens into an interior 10 of the filter fabric or membrane body 5.

At 11 a conical component is arranged, which opens into an outlet connection 12. The conical component 11 and the outlet connection 12 form part of a housing 18.

At 13, a disperse fluid phase is supplied from a container, also not shown, by means of a motor-driven pump (not shown).

The emulsion 14 leaves the housing 18 via the outlet connection 12.

At the Fig. 1 and 2 apparent embodiment, the filter fabric or membrane body 5 is eccentric, with defined adjustable eccentricity, to the housing 18, respectively.

In the embodiment according to Fig. 3 a flow installation (eg web 15) is arranged in the gap 3, which extends in the direction of the longitudinal axis 16 of the housing 18. The web 15 may also be helical or part of a spiral. It is also possible to provide within the gap 3 a plurality of such webs 15, spirals or helically extending ridges 3 of different cross-sectional geometry.

The diametrically oppositely directed arrows 17 are intended to indicate the approximately radially directed flow direction of the disperse fluid phase 13 with respect to the filter fabric or membrane body 5.

In Fig. 5 is a corresponding number sum distribution Q ₀ (x) with entry of the characteristic droplet sizes x _90,0 and x _10,0 whose ratio (x _90,0 / x _10,0 ) is used as a suitable measure for the droplet size distribution width, the representation for centric arrangement (Z) and eccentric arrangement (EZ) (and and Dehnströmanteile) were illustrated.

The operation of the apparent from the drawing embodiment is the following:

The disperse fluid phase 13 is pressed by means of the not shown, motor-driven pump via the provided with an inner bore 8 and thus designed as a hollow shaft rotating shaft 7 into the interior 10 of the rotating diaphragm cylinder body 6. The shaft 7 is dynamically sealed against the housing 18 by means of the mechanical seal 9. From there, the disperse fluid phase 13 passes through the membrane 5 applied to the cylinder body surface and forms the disperse drops 4 on its outside.

The continuous fluid phase 1 is passed through the port 2 in the cylindrical housing 18 and flows through the gap 3 between the rotating membrane or filter fabric body 5 and housing 18 in the axial direction. In this case, the disperse drops 4 formed on the membrane surface are flown. The intensity of the flow is determined by the circumferential speed of the membrane or filter cloth body or cylinder 6, the gap width 3 and the eccentricity or flow attachments (eg web (s), pins, knife / scraper) attached to the outer cylinder wall and the housing 18 fixed.

If between the diaphragm cylinder 6 and housing 18, an eccentric arrangement of the diaphragm cylinder 6 in the cylindrical housing 18 (FIG. Fig. 2 ), a mixed shear / elongation flow is formed which has improved dispersing properties. In order to achieve an improved droplet detachment from the membrane surface, it is also possible for the rotational flow to be defined with disturbing flow installations (for example web 15), preferably attached to the inner wall of the housing. Such flow internals (eg web 15) can be both straight and axially aligned, as well as helical, fitted.

The mixture of disperse drops 4 and continuous fluid phase 1, the emulsion 14, is formed at the exit from the gap 3 in an outlet geometry, which preferably consists of a conical component 11 and an outlet connection 12.

In Fig. 4 are emulsions produced by means of a rotating membrane (CPDN membrane = Controlled Pore Distance Membrane) as droplet size distribution function (number distribution qo (x)) for pure shear flow (concentric cylinders) and superimposed expansion flow (eccentric cylinders).

The features described in the summary, in the patent claims and in the description and apparent from the drawing features, both individually and in any combination for the realization of the invention may be essential.

LIST OF REFERENCE NUMBERS

1

Fluid phase, continuous

2

Connection, connection piece

3

Gap, annular gap, gap width

4

Drops, disperse

5

Membrane, membrane body, filter fabric body

6

Cylinder body, diaphragm cylinder

7

Rotary shaft, shaft, hollow shaft

8th

Bore, inner

9

Mechanical seal, dynamic

10

inner space

11

Component, conical

12

outlet connection

13

Fluid phase, disperse

14

emulsion

15

web

16

longitudinal axis

17

double arrow

18

casing

Claims (23)

1. Device for the mechanically careful generation of finely dispersed micro-/nano-emulsions with close drop size dispersal, where drops (4) are generated through a porous filter fabric or membrane body (5), in which a first fluid phase (13) is moved, particularly pressed, through these pores, and the drops (4) move away (are removed) from the filter fabric or membrane surface under their own motion in a second fluid phase (1) which is not mixable with the first and generate overlaid shear- and pronounced extensional flow components in the gap between the membrane cylinder and housing wall such that a preferably axisymmetric filter fabric and membrane body (5) is arranged in a surrounding housing (18) with a gap (3) of variable width so that it can be moved about its longitudinal axis under motor power.
2. Device in accordance with claim 1, characterised in that the filter fabric or membrane body (5) is shaped like a cylinder.
3. Device in accordance with claim 1, characterised in that the filter fabric or membrane body (5) is disk-shaped.
4. Device in accordance with claim 1 characterised in that the inner wall of the housing (18) delimiting the gap (3) and the filter fabric and membrane body (5) are arranged eccentrically.
5. Device in accordance with claim 1, characterised in that arranged in the gap (3) are one or more bars (15) as generator(s) for extensional current components.
6. Device in accordance with claim 5, characterised in that the bar (15) concerned extends in the longitudinal direction of the housing (18) and the filter fabric or membrane body (5).
7. Device in accordance with claim 5 or 6, characterised in that the bar (15) concerned is constructed straight or as a spiral or helix.
8. Device in accordance with claim 5 or any of the claims following it, characterised in that the bar (15) concerned is arranged on the inside of the housing (18).
9. Device in accordance with claim 1 or any of the claims following it, characterised in that the peripheral speed of the rotationally driveable filter fabric or membrane body (5) is between 1 m/s and 50 m/s.
10. Device in accordance with claim 1 or any of the claims following it, characterised in that the axial overflow rate of the cylindrical filter fabric or membrane body (5) is adjustable, particularly controllable or regulable, through the continuous fluid phase (1) independently of the peripheral speed of the filter fabric or membrane body (5).
11. Device in accordance with claim 1 or any of the claims following it, characterised in that the disperse fluid phase (13) is conducted via a hollow shaft (7) to the filter fabric or membrane body connected to this hollow shaft (7) and can be pressed through this filter fabric or membrane body (5) by means of pump pressure so that disperse fluid drops (4) can be produced on the surface of the filter fabric or membrane body (5).
12. Device in accordance with claim 1 or any of the claims following it, characterised in that the proper motion of the filter fabric or membrane body (5) can be adjusted via a control or regulation means.
13. Device in accordance with claim 1 or any of the claims following it, characterised in that the proper motion of the filter fabric or membrane body (5) can be undertaken via a computer program.
14. Device in accordance with claim 1, characterised in that the filter fabric or membrane body (5) can be rotated at an adjustable, constant speed.
15. Device in accordance with claim 1, characterised in that the filter fabric or membrane body (5) can be rotated at a periodically oscillating speed.
16. Device in accordance with claim 1, characterised in that the filter fabric or membrane body (5) is continuously or intermittently flowed through by the disperse fluid phase (13).
17. Device in accordance with claim 1, characterised in that before the filter fabric or membrane body (5) is flowed through by means of the disperse fluid phase (13) the filter fabric or membrane pore system is shortly flowed through by the continuous fluid phase (1) or another fluid which is not mixable with the disperse fluid phase (13) in order to wet the filter fabric or membrane pore walls of the filter fabric or filter fabric body (5) repellently for the disperse fluid phase (13).
18. Device in accordance with claim 1 or 14, characterised in that by the movement of the filter fabric or membrane body (5) predetermined, defined shear and/or extensional tensions can be set on the emulsion drops (4) formed on the filter fabric or membrane body (5).
19. Device in accordance with claim 1, characterised in that the filter fabric or membrane body (5) is subjected to an additional overflow perpendicular to the peripheral direction of the rotary motion, that means, e.g. in the case of a disk-shaped filter fabric or membrane body in a radial direction and in the case of a cylindrical filter fabric or membrane body (5) in an axial direction.
20. Device in accordance with claim 1, characterised in that, on the one hand, the fluid phase (13) flowing through the filter fabric or membrane body (5) constitutes an emulsion and thus after the drops (4) formed have moved away from the filter fabric or membrane surface in a further fluid phase a double emulsion of the water/oil/water or oil/water/oil type is formed.
21. Device in accordance with claim 1, characterised in that, on the other hand, the fluid phase (1) created at the surface of the filter fabric or membrane body (5) constitutes a suspension which, after the drops (4) have been carried away, in a further surrounding fluid phase forms a suspension/emulsion system.
22. Device in accordance with claim 1 or any of the claims following it, characterised in that the motor drive for the pump pumping the fluid phase (13) can be driven intermittently according to a predetermined program.
23. Device in accordance with claim 1 or any of the claims following it, characterised in that the motor drive for the pump pumping the disperse phase (1) can be driven intermittently in accordance with a predetermined program.

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