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
2001-08-28
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, C210S800000, C366S173100, C366S176100, C366S176400, C366S340000, C516S924000
Reexamination Certificate
active
06281254
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microchannel apparatus for producing emulsions used in the food industry, the manufacturing of drugs and cosmetics, etc., and to a method of producing emulsions making use thereof.
2. Description of Related Art
Techniques in which a biphasic system, for which a separated state is thermodynamically stable, is formed, 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 of 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 by means of 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 KOOGAKU 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 comprising particles larger than the membrane pores and cannot separate particles smaller than the membrane pores. These methods are, therefore, especially unsuitable for producing emulsions comprising large particles. In addition, these methods using a membrane are unsuitable for industrially mass producing emulsions.
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 which can produce homogenous emulsions continuously in International Publication No. WO97/30783.
The structure of this apparatus is shown in
FIGS. 10 and 11
.
FIG. 10
is a vertical sectional view of this apparatus and
FIG. 11
shows a base and a plate taken apart.
In this apparatus for producing emulsions, a supply port
101
for a continuous phase (W) is formed in a side wall of a body
100
, a supply port
103
for a dispersed phase (O) is formed in the center of a lid
102
which closes an upper opening of the body
100
, and a withdrawal ports
104
for emulsions (E) are formed at a place apart from the center. A bulkhead member
106
formed between the lid
102
and the base
105
separates the supply port
103
for the dispersed phase (O) from the withdrawal ports
104
for emulsions (E). In addition, a supply port
107
for the dispersed phase (O) is formed in the center part of the base
105
, a gap
109
is formed between the base
105
and the plate
108
placed opposite the base
105
, a boundary section
110
formed in the base
105
separates the dispersed phase (O) and the continuous phase (W), and via a microchannel
111
formed in the boundary section
110
the dispersed phase (O) and the continuous phase (W) are mixed.
The dispersed phase (O) supplied to the inside of the bulkhead member
106
via the supply port
103
enters the gap
109
between the plate
108
and the base
105
via the supply port
107
and this dispersed phase (O) enters the continuous phase (W) through the microchannels in the boundary section
110
, thereby forming emulsions.
In addition, the inventors of the present invention have proposed other microchannel apparatuses, as improvements of the apparatus disclosed in International Publication No. WO97/30783, in Japanese Patent Application Nos. 10-83946 and 10-187345.
In the apparatus proposed in Japanese Patent Application No. 10-83946, emulsions are easily withdrawn by orienting the apparatus shown in
FIG. 10
in a vertical direction or inclined and using differences in specific gravity between the dispersed phase and the continuous phase. The apparatus proposed in Japanese Patent Application No. 10-187345 is a cross-flow apparatus which pumps the dispersed phase into the continuous phase continuously flowing from one side and it is very effective for continuously producing emulsions.
FIG. 12
is an enlarged view of the microchannel part of the apparatus disclosed in International Publication No. WO97/30783, as well as in Japanese Patent Application Nos. 10-83946 and 10-187345.
The microchannels
111
are formed between convex portions
112
. Because of the differences in size of each microchannel and the positions in which microchannels are formed, the pressure to obtain break-through (i.e. pressure at which production of microspheres starts) differs in each microchannel.
Accordingly, as shown in
FIG. 12
, of the base, in the case of applying low pressure to the dispersed phase, microspheres (fine particles of dispersed phase) are formed only in one or another specific microchannel, so as to obtain very homogenous microspheres. However, it is unsuitable for mass production because the rest and indeed most of the microchannels do not take part in producing the microspheres.
On the other hand, as shown in FIGS.
13
(
a
) and
13
(
b
), in the case of applying considerably high pressure to the dispersed phase in order to produce microspheres from all microchannels in the previously proposed apparatus, to make mass production more efficient, adjacent microspheres connect and unite with each other, so as to grow large.
SUMMARY OF THE INVENTION
The inventors achieved the present invention based on their determination that microspheres in the course of growing, i.e. which have not become perfect spheres yet, can easily unite with each other when they connect or come into contact, and conversely microspheres which have already become perfect spheres have difficulty in uniting to each other even if they should connect.
Therefore, there is provided in accordance with the present invention a microchannel apparatus, comprising: a plurality of microchannels having a predetermined width formed in a boundary section between a dispersed phase region and a continuous region phase in which the dispersed phase may be pumped into the continuous phase via said microchannels to form microspheres; wherein said microchannels are formed between fine convex portions and a partition wall is formed from at least one said convex portions toward the continuous phase.
The microspheres tend not to unite with each other because microspheres pumped from a microchannel will not connect to microspheres pumped from an adjacent microchannel on the condition that the microspheres have become nearly perfect spheres, due to the presence of the partition wall. Accordingly, it is possible to mass produce homogenous and fine microspheres.
There is also provided in accordance with the present invention, a microchannel apparatus as the application of the form of microchannels defined in above to the cross-flow apparatus proposed in Japanese Patent Application No. 10-187345, comprising: a base which is accommodated in a case and a plate which is installed on a side of the ba
Kikuchi Yuji
Largueze Christophe
Nabetani Hiroshi
Nakajima Mitsutoshi
Blackman William D.
Carrier Jpseph P.
Carrier Blackman & Associates P.C.
Japan as represented by Director of National Food Research Insti
Lovering Richard D.
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