JP2006102585A - Manufacturing method of fine particles and microflow channel device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of fine particles capable of stably forming particles having a particle size distribution containing no unnecessary material for a long period of time. <P>SOLUTION: In the manufacturing method of fine particles, a first fluid flowing through a first flow channel 3-1 at a constant speed and a second fluid flowing through a second flow channel 3-2 at a constant speed are allowed to meet with each other and the vicinity of the flow channel meeting part is irradiated with pulse lasers condensed at constant time intervals. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing fine particles, such as spacers for forming minute gaps and toner for forming high-definition images. The present invention relates to a microchannel device to be used.

Even substances that do not normally mix with each other, such as water and oil, can be apparently mixed by dispersing one of the substances as fine particles. This phenomenon is called emulsification. . In order to maintain such an emulsified state, the dispersed particles need to have a relatively uniform diameter. As a method of dispersing a substance as particles, a method of dispersing by a shearing force generated by stirring with a mixer or a homogenizer is known.
According to this method, there is a correlation between the shearing force generated during stirring and the diameter of the obtained particles, and particles having an average particle diameter corresponding to the stirring speed can be produced. However, since the stirring speed and shearing force obtained by stirring the inside of a container having a certain volume with stirring means such as one or a plurality of mixers vary depending on the location in the container, the obtained particle size distribution is relatively There is a problem that it becomes wide.
In addition, when the particle size distribution is wide, a plurality of generated particles are likely to coalesce with time, and a large amount of surfactant is added to avoid this. However, the surfactant is often unnecessary as the original function of the particles, and when the surfactant is added, it is necessary to remove the surfactant by adding a large amount of water resources in a subsequent process. Further, the particle size distribution can be suppressed to some extent by taking a long stirring time, but this requires a long time and a large amount of energy.
In recent years, in order to produce particles with a uniform particle size distribution, a micro flow channel having a T-shaped or Y-shaped confluence is formed, and water or oil as a continuous phase is flowed from one end thereof, and from the other end. Flow the dispersed phase in which particles are to be formed (oil if the continuous phase is water, water if the continuous phase is oil) at a lower flow rate than the continuous phase, and cut the dispersed phase by the shearing force of the continuous phase at these junctions. A method of making particles into particles (for example, http://www.intellect.pe.u-tokyo.ac.jp/research/emulsion/micro_channel_j.html) has been proposed. As related technologies, for example, there are technologies described in Patent Documents 1 and 2.

FIG. 9 is an explanatory diagram of a particle generation process by the merging of two fluids using a microchannel according to a conventional example. A fluid that is a continuous phase is flowed from one of the two flow paths 3-1 and 3-2 that are bifurcated among the three Y-shaped flow paths, and the other flow path 3-2. A fluid that forms more particles is allowed to flow as a dispersed phase at a lower flow rate than the continuous phase. At this time, it is desirable that the inner wall of the flow path be subjected to a material or treatment that is difficult to wet with respect to the dispersed phase and easy to wet with respect to the continuous phase. Then, in the vicinity of the flow path merging portion, the dispersed phase merges in a state where the continuous phase is in contact with the wall surface and not in contact with the flow path.
In such a state, a shearing force acts on the disperse phase due to a fast flow of the continuous phase, and the particles are cut into particles and flow downstream. At this time, since the continuous phase and the dispersed phase flow at a constant speed and the force acting as a shearing force is constant, particles having a uniform size determined by the flow velocity and viscosity are formed from the dispersed phase (see FIG. 9 (1)).
JP 9-225291 A JP 2003-126686 A

However, when a dispersed phase having a viscosity higher than that of the continuous phase is used, the dispersed phase approaches the wall surface due to the force exerted by the continuous phase and flows almost in contact with the wall surface on the continuous phase flow path side. As a result, the particles are cut downstream from the joining portion, and the particle diameter obtained at this time has a wider distribution than the above-described state (FIG. 9 (2)).
If the liquid-repellent treatment of the flow path wall surface is insufficient or dust or the like is mixed in the fluid, the initial stage of particle generation may be good as shown in FIG. It becomes like (2). Finally, particles may not be generated at all as shown in FIG. 9 (3). This tendency is particularly remarkable when an aqueous phase is used as the continuous layer and an oil phase having a higher viscosity than the continuous layer is used as the dispersed layer.
An object of the present invention is to provide a method for producing microparticles and a microchannel device capable of stably forming particles having a small particle size distribution without containing unnecessary materials over a long period of time.

In order to achieve the above object, the first aspect of the present invention provides a first fluid that flows through the first flow path at a constant speed and a second fluid that flows through the second flow path at a constant speed. The most important feature is a method for producing fine particles that are irradiated and irradiated with a pulsed laser focused at a fixed time interval in the vicinity of the flow path merging portion.
According to a second aspect of the present invention, there is provided the method for producing a microparticle according to the first aspect, wherein the irradiation direction of the pulse laser is a microparticle that is perpendicular to a plane including the first channel and the second channel. The manufacturing method is the main feature.
The invention according to claim 3 is characterized in that, in the method for producing microparticles according to claim 2, the method for producing microparticles in which the focused position of the irradiating pulse laser exists in the fluid in the laser beam traveling direction is a main feature. .
The invention according to claim 4 is the method for producing microparticles according to claim 2 or 3, mainly comprising the method for producing microparticles in which the focused position of the pulse laser to be irradiated is in the first fluid within the irradiation surface. Features.
The invention according to claim 5 is the method for producing microparticles according to claim 1, wherein the irradiation direction of the pulse laser is parallel to the plane including the first flow path and the second flow path. The manufacturing method is the main feature.
The invention according to claim 6 is characterized in that, in the method for producing microparticles according to claim 5, the method for producing microparticles in which the focused position of the pulse laser is in the first fluid in the laser beam traveling direction is the main feature. .
The invention according to claim 7 is characterized in that, in the method for producing microparticles according to any one of claims 1 to 6, the method for producing microparticles in which the pulse width of the pulse laser used for irradiation is 1 ns or less. To do.

The invention described in claim 8 is mainly a method for producing microparticles according to any one of claims 1 to 7, wherein the boiling point of the first fluid used is lower than the boiling point of the second fluid. Features.
The invention according to claim 9 is a flow channel device having a structure including at least a first flow channel and a second flow channel that merges with the first flow channel, and further having a lid on the upper portion of the flow channel. The micro flow channel device in which the vicinity of the flow path merging portion is made of a light transmitting member and an optical element having a light collecting action is formed on the light transmitting member is the main feature.
The invention according to claim 10 is characterized in that, in the microchannel device according to claim 9, the microchannel device in which the optical element is a convex lens.
An eleventh aspect of the invention is characterized in that, in the microchannel device according to the ninth aspect, the microchannel device in which the optical element is a diffractive optical element.
The invention according to claim 12 is a flow channel device having a structure including at least a first flow channel and a second flow channel that merges with the first flow channel, and further having a lid provided on an upper portion of the flow channel. Most important is a microchannel device in which the vicinity of the channel confluence is made of a light transmitting member, and the channel portion facing the light transmitting member is made of a member that reflects light and has an optical element with a light collecting function. Features.
A thirteenth aspect of the invention is characterized in that, in the microchannel device according to the twelfth aspect, the microchannel device in which the optical element is a concave mirror.

In the method for producing microparticles of the present invention, a part of the fluid is vaporized at a constant time interval, and the particles can be reliably formed to break the flow in the fluid.
Further, since the condensing position of the laser to be irradiated is in the fluid and further in the first fluid, the particles are manufactured without causing thermal damage to the flow path, the constituent members, and the second fluid as the material of the particles. be able to.
Also, since laser light with a very short pulse width is used, thermal effects occur only in very small regions with high photon density, which can significantly reduce damage and thermal effects other than necessary parts. it can.
In addition, since the first fluid has a low melting point and is surely vaporized first, the particles of the second fluid can be reliably produced.
In the micro-channel device of the present invention, the lid near the channel merging portion can transmit light and is provided with an optical element having a light collecting function. By irradiating more light, it is possible to create a region with high photon density by condensing in the fluid near the confluence.
In addition, an optical element having a condensing function is formed in the vicinity of the flow path merging portion, and the lid portion facing this portion can transmit light. The introduced light can be collected in the fluid in the vicinity of the flow path confluence and a region with a high photon density can be created.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view of a method for producing fine particles according to an embodiment of the present invention. Similarly to FIG. 9, for a microchannel device having a Y-shaped channel, a continuous phase (first fluid) is supplied to the first channel 3-1 at a constant flow rate by a liquid feeding means (not shown). A material (second fluid) that becomes a dispersed phase is allowed to flow through the second flow path 3-2 at a constant flow rate smaller than that of the continuous phase (FIG. 1 (1)). Reference numeral 3-3 denotes a flow path junction. The arrows in the figure indicate the liquid feeding direction.
In the present invention, in the Y-shaped channel that is joined to one third channel from the junction of the first and second channels 3-1 and 3-2 that are bifurcated, it is constant. A first fluid (continuous phase) that flows through the first flow path 3-1 at a speed of 2 mm and a second fluid (dispersed phase) that flows through the second flow path 3-2 at a constant speed, In order to divide the flow in the second fluid by irradiating a part of the second fluid by irradiating the vicinity of the flow path confluence with a pulsed laser beam focused at a constant time interval. It is possible to reliably form particles having a predetermined particle diameter.
Since the focused position of the pulse laser to be irradiated exists in the first fluid in the laser beam traveling direction, the particles are formed without causing thermal damage to the flow path, the constituent members, and the second fluid that is the material of the particles. be able to.
In the present invention, a condensing element is disposed at an appropriate position in the flow path and in the vicinity of the merge portion so that the pulsed laser light transmitted through the material constituting the flow path is condensed in the fluid. The means for condensing the pulse laser beam will be described later.
In this state, a short pulse laser is irradiated to the region including the condensing element at a constant interval. Of the laser light, the light incident on the condensing element is condensed and focused in the fluid. Because the laser beam used for irradiation has a short pulse width, it reaches a peak power of several megawatts and is focused on a very small area by a lens. Absorption is caused by a nonlinear effect and heat is generated. The fluid in the region condensed by this heat is instantaneously heated and vaporized to generate bubbles. The fluid on the downstream side in the flow path is divided by the bubbles (FIG. 1 (2)).

Since the irradiated light is for a very short time, the vaporized portion is cooled and immediately returned to the liquid phase. At this time, since the flow rate of the continuous phase is large and the volume occupied in the flow path is large, it is integrated with the front and back liquid phases to form a continuous phase again. On the other hand, since the flow rate of the dispersed phase is small, it flows downstream while forming a spherical shape under the influence of surface tension in an isolated state, and particles are formed (FIG. 1 (3)).
At this time, since the flow rate of each fluid and the irradiation interval of the pulse laser are constant, the volume of the dispersed phase cut by the generated bubbles is constant, and as a result, particles having a uniform particle diameter are obtained. It is desirable that the laser beam to be irradiated has a short pulse width. This means that the shorter the pulse width, the larger the peak power even if the output is the same, and efficient heating can be achieved in a short time. By condensing this, it becomes possible to further select and heat the region.
That is, in the state where it is not condensed, it is hardly heated even if it is irradiated, and only the part condensed to a certain area or less can be heated to the boiling point or more and vaporized. If this condensing place can be limited to the inside of the continuous phase, the dispersed phase hardly changes in temperature and can be made into particles. This is particularly effective when a material that is altered by temperature is made into particles.
Further, heat can be prevented from being applied to the flow channel device, and the flow channel device can be used over a long period of time. Further, the laser beam may be perpendicular (orthogonal) to the flow path substrate surface (a plane including the first flow path and the second flow path) as shown in FIG. 7, or as shown in FIG. Irradiation can be performed in parallel to the flow path substrate surface.
In addition, by constructing the focused position of the pulse laser to be irradiated within the first fluid within the irradiation surface, it is possible to effectively prevent thermal damage to the second fluid, which is the material of the flow path, the constituent members, and the particles. Can be prevented.
In addition, since the pulse width used for irradiation is set to a very short pulse width (for example, 1 ns or less), a thermal effect occurs only in a very small region where the condensed photon density is high. Damage and thermal effects can be reduced.
Moreover, by setting the boiling point of the first fluid to be used to be lower than the boiling point of the second fluid, the second liquid is surely vaporized, and the particles of the second fluid can be easily formed.

Next, a method of introducing pulsed laser light into the flow channel and a flow channel device that realizes the method will be described. FIG. 7 is a configuration diagram (No. 1) of a general micro-channel device, and FIG. 8 is a configuration diagram (No. 2) of a general micro-channel device. Reference numeral 1 denotes a lid, 2 denotes a flow path substrate, 3 denotes a flow path, and 4 denotes a light collecting element. As shown in FIGS. 7 and 8, the condensing element 4 is arranged between the laser light generating means and the flow path 3, and the laser light is introduced into the flow path 3 and condensed in the fluid. be able to.
However, in this configuration, a relatively long distance is required as the focal length of the condensing element 4, and the condensing spot of the laser beam obtained as a result becomes relatively large, and the area of the fluid to be heated becomes large. End up. Therefore, it is desirable that the condensing element is formed integrally with the flow path device, the focal distance thereof is shortened, and the condensing spot diameter is reduced as described below.
FIG. 2 is a configuration diagram of the microchannel device according to the first embodiment of the present invention, where (1) shows the configuration of the lid 1 and (2) shows the configuration of the channel substrate 2. Actually, the lid 1 is bonded on the flow path substrate 2, the two inflow ports 5 are connected to the liquid feeding means (not shown), and the outflow port 6 is connected to the particle recovery means (not shown). .
The lid 1 is made of a transparent material such as glass or resin, and a convex lens is formed as a condensing element 4 at a portion facing the flow path merging portion 3-3. As the condensing element 4, any of a gradient index lens, a Fresnel lens, and a diffractive optical element can be used in addition to the convex lens.
That is, the present embodiment has a structure in which at least a first flow path 3-1 and a second flow path 3-2 that merges with the first flow path are provided, and a lid 1 is provided on the upper portion of the flow path. The flow path device is characterized in that the vicinity of the flow path merging portion is formed of a light transmitting member, and an optical element having a light collecting function is formed on the light transmitting member.
As described above, in the microchannel device of the present invention, the lid portion 1 in the vicinity of the channel merging portion can transmit light and the optical element 4 having a light collecting function is provided. On the other hand, by irradiating light from outside the flow path, it is possible to create a region having a high photon density by condensing in the fluid in the vicinity of the merging portion.

FIG. 3 is a configuration diagram of a microchannel device according to a second embodiment of the present invention, where (1) shows a lid and (2) shows a channel substrate. It consists of a lid 1 and a flow path substrate 2 and includes an inflow port 5 and an outflow port 6, and both are actually joined.
The lid 1 is made of a transparent material such as glass or resin, the flow path substrate 2 is made of a member having a high light reflectivity at least on the flow path surface (inner surface). A spherical concave surface (reflective surface) is formed as the reflective condensing element 4 on the bottom surface in the vicinity of the three flow path confluence portions 3-3. The other parts are the same as in FIG. In either case, the focal distance can be set to a very short distance of about the depth or width of the channel.
FIG. 4 is a configuration diagram of a microchannel device according to a third embodiment of the present invention. A condensing element 4 formed on the outer surface of the lid 1 is disposed at the center of the flow path 3.
FIG. 5 is a configuration diagram of a microchannel device according to a fourth embodiment of the present invention. A condensing element 4 formed on the outer surface of the lid 1 is arranged not on the center of the flow path 3 but on the continuous phase side.
With this arrangement, the position where the laser beam is focused is in the continuous phase, and the dispersed phase is not irradiated with the focused laser beam. Can be generated. As a result, particles can be formed without any influence even if a material that is easily altered by heat is used as the dispersed phase.
FIG. 6 is a configuration diagram of a microchannel device according to a fifth embodiment of the present invention. A condensing element (concave reflecting surface = concave mirror) 4 having a spherical concave surface is formed in the flow path 3. Since the flow path 3 is formed of a member that reflects light, the light irradiated to the flow path 3 through the lid 1 is reflected by the flow path 3. At this time, the light irradiated on the concave surface is collected and is focused in the fluid, and bubbles are generated as described above. As a result, particles having a uniform particle size can be obtained.
In this way, the optical element 4 having a condensing function is formed by reflection in the vicinity of the flow path merging portion, and the lid portion 1 facing this portion can transmit light. Light introduced from the outside of the device can be collected in the fluid near the flow path confluence and a region with a high photon density can be created.

Explanatory drawing of the manufacturing method of the microparticle which concerns on embodiment of this invention. 1 is a configuration diagram of a microchannel device according to a first embodiment of the present invention. The block diagram of the microchannel device which concerns on the 2nd Embodiment of this invention. The block diagram of the microchannel device which concerns on the 3rd Embodiment of this invention. The block diagram of the microchannel device which concerns on the 4th Embodiment of this invention. The block diagram of the microchannel device which concerns on the 5th Embodiment of this invention. The block diagram of the general microchannel device (the 1). The block diagram of the general microchannel device (the 2). Explanatory drawing of the particle | grain production | generation process by 2 fluid confluence | merging using the microchannel based on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lid, 2 flow path board | substrates, 3 flow paths, 3-1 1st flow path, 3-2 2nd flow path, 3-3 flow path confluence | merging part, 4 Light condensing element, 5 inflow port, 6 outflow port

Claims (13)

  The first fluid that flows through the first flow path at a constant speed and the second fluid that flows through the second flow path at a constant speed are merged and collected at a constant time interval in the vicinity of the flow path confluence. A method for producing fine particles, characterized by irradiating a pulsed laser beam.   2. The method for producing fine particles according to claim 1, wherein the irradiation direction of the pulse laser is orthogonal to a plane including the first flow path and the second flow path.   3. The method for producing fine particles according to claim 2, wherein the focused position of the pulse laser to be irradiated is present in the fluid in the laser beam traveling direction.   4. The method for producing fine particles according to claim 2, wherein the focused position of the pulse laser to be irradiated is in the first fluid within the irradiation surface.   2. The method for producing fine particles according to claim 1, wherein the irradiation direction of the pulse laser is parallel to a plane including the first channel and the second channel.   6. The method for producing microparticles according to claim 5, wherein the condensing position of the pulse laser is in the first fluid in the laser beam traveling direction.   The method for producing microparticles according to any one of claims 1 to 6, wherein the pulse width of the pulse laser used for irradiation is 1 ns or less.   The method for producing microparticles according to any one of claims 1 to 7, wherein the boiling point of the first fluid used is lower than the boiling point of the second fluid.   In a flow channel device having a structure in which at least a first flow channel and a second flow channel that merges with the first flow channel are provided, and a lid is provided on the upper portion of the flow channel, the vicinity of the flow channel merge portion is light transmissive. A microchannel device comprising a member, and an optical element having a condensing function formed on the light transmitting member.   10. The microchannel device according to claim 9, wherein the optical element is a convex lens.   The microchannel device according to claim 9, wherein the optical element is a diffractive optical element.   In a flow channel device having a structure in which at least a first flow channel and a second flow channel that merges with the first flow channel are provided, and a lid is provided on the upper portion of the flow channel, the vicinity of the flow channel merge portion is light transmissive. A microchannel device comprising a member, wherein a channel portion facing the light transmitting member is formed of a member that reflects light, and an optical element having a condensing function is formed. 13. The microchannel device according to claim 12, wherein the optical element is a concave mirror.

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