Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Aqueous continuous liquid phase and discontinuous phase...
Reexamination Certificate
1999-03-01
2001-07-10
Lovering, Richard D. (Department: 1712)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Aqueous continuous liquid phase and discontinuous phase...
C137S003000, C137S896000, C210S802000, C366S173100, C366S176100, C366S176400, C366S340000, C516S197000, C516S924000
Reexamination Certificate
active
06258858
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cross-flow type microchannel apparatus for producing and separating emulsions used in the food industry, manufacturing of drugs and cosmetics, etc. and to a method of producing and separating emulsions making use thereof.
2. Description of Related Art
Techniques in which a biphasic system for which a separated state is thermodynamically stable, such as that composed of a water phase and an organic phase which are emulsified to obtain a semi-stable emulsion, are conventionally known. As general emulsification methods, there have been described in “Science of Emulsions” (Asakura-shoten, 1971), the methods using a mixer, a colloid mill, a homogenizer, etc., and the method of dispersion with sound waves, which are all well-known.
The general methods mentioned above have a disadvantage in that diameters of dispersed phase particles in a continuous phase are distributed over a wide range.
Therefore, a method of using filtration through a membrane comprising polycarbonate (Biochemica et Biophysica Acta, 557 (1979), North Holland Biochemical Press); a method using repeated filtrations through a PTFE (polytetrafluoroethylene) membrane (Proceedings of the 26th Autumn Meeting of the Society of Chemical Engineers, Japan, 1993); and, a method of manufacturing homogenous emulsions by transferring a dispersed phase into a continuous phase through a porous glass membrane having uniform pores (Japanese Patent Application Laid-Open No. 2-95433), have been proposed.
As a method of producing emulsions using a nozzle or a porous plate, a laminar-flow dripping method (KAGAKU K{overscore (O)}GAKU Vol. 21, No. 4, 1957) is also known.
The method using filtration through a membrane comprising polycarbonate and the method using repeated filtrations through a PTFE membrane theoretically cannot manufacture emulsions of particles larger than the membrane pores and cannot separate particles smaller than the membrane pores. These methods are therefore especially unsuitable for producing emulsions of large particles.
In the method using a porous glass membrane having uniform pores, when the average diameter of the membrane pores is small, particle diameters are distributed in a narrow range and thus homogenous emulsions can be obtained. When the average diameter of the membrane pores is increased, however, particle diameters become distributed over a wide range so that homogenous emulsions cannot be obtained.
In addition, in the laminar-flow dripping method, particle sizes become 1,000 &mgr;m or more and are distributed over a wide range so that homogenous emulsions cannot be obtained.
Therefore, the inventors of the present invention formerly proposed an apparatus for producing emulsions which can solve the above-mentioned problems and disadvantages of the known methods in Japanese Patent Application Laid-Open No. 9-225291.
As shown in
FIG. 10
, in this apparatus, a supply port
101
for a dispersed phase is formed in a center part of a base
100
, a gap
103
to which the dispersed phase is supplied is formed between the base
100
and a plate
102
placed opposite the base
100
, a large number of microchannels
104
having a predetermined width are formed in a boundary section between the dispersed phase and a continuous phase, the dispersed phase is brought into contact with the continuous phase via the microchannels
104
, and the pressurized dispersed phase is mixed into the continuous phase as microspheres and obtained emulsions are withdrawn from a withdrawal ports
105
.
In the apparatus disclosed in Japanese Patent Application Laid-Open No. 9-225291, the dispersed phase is spread from the supply port
101
formed in the center part of the base to the microchannels
104
formed to surround this supply port. Therefore, it is necessary to apply considerably high pressure to the supply port
101
in order to obtain sufficient pressure to obtain break-through at the microchannels.
In order to improve this problem, the inventors of the present invention have proposed an apparatus for withdrawing emulsions by using differences in specific gravity (differences in density) and floating emulsions. This apparatus is workable when the difference in specific gravities is sufficiently large, however, it cannot withdraw emulsions effectively when the difference in specific gravities is small.
On the other hand, in the case of separating emulsions by using the apparatus disclosed in Japanese Patent Application Laid-Open No. 9-225291, if emulsions are supplied from the supply port
101
formed in the center part of the base and the continuous phase is withdrawn via the microchannels
104
, there is a block created at the inside part of the microchannels by the dispersed phase for a short time. Conversely, if emulsions are supplied to the outside region of the microchannels, a block is created at the outside part of the microchannels of the dispersed phase for a short time.
SUMMARY OF THE INVENTION
To solve the above-mentioned problems of the known, and proposed methods and apparatus, there is provided in accordance with the present invention a cross-flow microchannel apparatus for producing emulsions, comprising: a case; a base which is accommodated in the case; and, a plate which is installed on a side of the base for forming a flow path beside or at the side of the base; wherein the case has formed therein a supply hole for a continuous phase, a supply hole for a dispersed phase, and a withdrawal hole for emulsions are formed, and in the base are formed, a supply port for the continuous phase corresponding to the supply hole for the continuous phase, a withdrawal port for emulsions corresponding to the withdrawal hole for emulsions, and microchannels opening to the flow path; and furthermore, via the microchannels, a region of the dispersed phase at the outside of the base and the flow path for the continuous phase at the inside of the base are connected.
There is also provided in accordance with the present invention a cross-flow microchannel apparatus for separating emulsions, comprising: a case, a base which is accommodated in the case, and a plate which is installed on a side of the base for forming a flow path beside the base, wherein: in the case, a supply hole for emulsions, a withdrawal hole for a continuous phase, and a withdrawal hole for at least one of a dispersed phase and emulsions are formed, and in the base, a supply port for emulsions corresponding to the supply hole for emulsions, a withdrawal port for the dispersed phase or emulsions corresponding to the withdrawal hole for the dispersed phase or emulsions, and microchannels opening to the flow path are formed; and furthermore, via the microchannels, the region of continuous phase at the outside of the base and the flow path for emulsions at the inside of the base are connected.
The separation of the emulsions includes removing particles having diameters which are less than a certain value from the emulsions. Essentially, the apparatus of the invention is the same for producing emulsions from continuous and dispersed phases, and for separating emulsions into continuous and dispersed phases, although the supply and withdrawal holes/ports in the apparatus would be used in relation to different ones of the emulsions, continuous phase and dispersed phase depending on what the apparatus is used for.
In the above-mentioned apparatus, a horizontal terrace may be formed from the microchannels to a flow path at the inside of the base as a form of microchannels. It becomes clear that forming a terrace makes a dispersed phase having larger diameter components enter into a continuous phase.
It is preferable to make a part of the base a taper-like notch, so that pressure is concentrated to the microchannels, and thereby it is possible to effectively produce emulsions by using lower pressure.
It is possible to make the structure simple by making a plate which forms a flow path between the base combined with a lid body which covers a concave portion of the case which re
Kawakatsu Takahiro
Kikuchi Yuji
Komori Hideaki
Nakajima Mitsutoshi
Yonemoto Toshikuni
Blackman William D.
Carrier Joseph P.
Carrier Blackman & Associates P.C.
Japan as Represented by Director of National Food Research Insti
Lovering Richard D.
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