JP2020151674A - Supercritical fluid dispersion method - Google Patents

Abstract

To provide a supercritical fluid dispersion method having both excellent fluidity during processing and easiness of separation after processing, by using supercritical fluid for fluid to be mixed with an object to be processed.SOLUTION: A supercritical fluid dispersion method includes the first supercritical fluid dispersion step for obtaining the first dispersion by dispersing an object to be processed into supercritical fluid, and the second supercritical fluid dispersion step for obtaining the second dispersion by pressurizing and supplying the first dispersion to an orifice homogenizer part having a small-diameter passage part, and by miniaturizing the object to be processed in the first dispersion, and further includes, after the second supercritical fluid dispersion step, an isolation step for isolating a microminiaturization object of the object to be processed by removing the supercritical fluid from the second dispersion.SELECTED DRAWING: Figure 1

Description

The present invention relates to a supercritical fluid dispersion method, and more particularly to a method of dispersing an object to be treated in a supercritical fluid to reduce the size.

As a method for miniaturizing the object to be treated, a conventional dry or wet pulverizer in which a dry or wet pulverizer is used has not been suitable for pulverizing a small amount. The inventor has long realized efficient miniaturization of a small amount of the object to be processed by flowing the mixture of the object to be processed and the fluid while pressurizing the inside of the capillary tube (see, for example, Patent Document 1). ..

When flowing the mixture in the capillary tube, it was necessary to flow it at a high speed from the viewpoint of processing efficiency, and the mixture was flowed at a very high pressure. In particular, in the case of water or an organic solvent, the viscosity becomes high in the state of a mixture of the object to be treated and the fluid, and the fluidity tends to decrease. Therefore, a high output is required for the pump for pumping, and the scale of the device itself tends to be large. In addition, since the piping receives a pressure load when the mixture flows, pressure-resistant construction is required. Therefore, the equipment burden for miniaturization is large.

Further, it is necessary to separate the target miniaturized object to be treated from the mixture of the miniaturized object to be treated and the fluid serving as a solvent after the miniaturization process is completed. The use of water and organic solvents may require ex post separation treatment such as evaporation.

Japanese Unexamined Patent Publication No. 2018-100474

Therefore, the inventor has desired a method for miniaturizing the object to be treated, which can be easily separated after the treatment, while maintaining good fluidity of the fluid mixed with the object to be treated. The present invention has been made in view of the above points, and by using a supercritical fluid as the fluid to be mixed with the object to be treated, a supercritical fluid having both good fluidity during treatment and ease of separation after treatment. Provide a distribution method.

That is, the first form is a first supercritical fluid dispersion step of dispersing an object to be treated in a supercritical fluid to obtain a first dispersion, and an orifice in which the first dispersion is provided with a small-diameter flow path portion. It is characterized by comprising a second supercritical fluid dispersion step of pressurizing and supplying to the homogenizer portion to miniaturize the object to be treated in the first dispersion to obtain a second dispersion.

In the second embodiment, in the second supercritical fluid dispersion step, after the first dispersion passes through the orifice homogenizer portion, the first dispersion after passing passes through the orifice homogenizer portion again, and the second dispersion is repeatedly used. Is prepared.

The third embodiment is characterized in that after the second supercritical fluid dispersion step, an isolation step of removing the supercritical fluid from the second dispersion and isolating microparticles of the object to be treated is added.

The fourth form is characterized in that the supercritical fluid is a supercritical fluid of carbon dioxide.

In the fifth form, the orifice homogenizer portion is composed of a plurality of inflow side flow path portions, a plurality of outflow side flow path portions, a gathering portion that singly aggregates a plurality of inflow side flow path portions, and a downstream portion of the assembly portion. It is characterized by including an orifice flow path portion connected to the above, and a branch portion connected to the downstream side of the orifice flow path portion to branch the orifice flow path portion and connect to a plurality of outflow side flow path portions.

According to the supercritical fluid dispersion method of the present invention, the first supercritical fluid dispersion step of dispersing the object to be treated in the supercritical fluid to obtain the first dispersion, and the first dispersion are provided with a small-diameter flow path portion. A process of miniaturizing the object to be treated is provided with a second supercritical fluid dispersion step of pressurizing and supplying to the orifice homogenizer portion to obtain a second dispersion by miniaturizing the object to be processed in the first dispersion. It can have both good fluidity at the time and easy separation of the fluid that becomes the solvent after the treatment.

It is an overall block diagram of the supercritical fluid dispersion apparatus of 1st Embodiment which carries out the supercritical fluid dispersion method. It is a vertical cross-sectional view of the main part of an orifice homogenizer part. It is sectional drawing of the main part of the orifice homogenizer part. It is 1st schematic explanatory drawing at the time of movement of the supercritical fluid dispersion apparatus of 1st Embodiment. It is a 2nd schematic explanatory drawing at the time of movement of the supercritical fluid dispersion apparatus of 1st Embodiment. It is 1st schematic explanatory drawing at the time of movement of the supercritical fluid dispersion apparatus of 2nd Embodiment. It is a 2nd schematic explanatory drawing at the time of movement of the supercritical fluid dispersion apparatus of 2nd Embodiment. It is a 3rd schematic explanatory drawing at the time of movement of the supercritical fluid dispersion apparatus of 2nd Embodiment.

In explaining the supercritical fluid dispersion method of the present invention, it will be described with reference to the overall configuration diagram of the supercritical fluid dispersion device 1 (first embodiment) of FIG. Of course, since the illustrated device is a disclosure of one embodiment, the configuration for realizing the supercritical fluid dispersion method of the present invention is not limited to the illustrated embodiment.

The illustrated supercritical fluid dispersion device 1 includes a raw material tank 30, a branch block 40, an orifice homogenizer section 10, and a pump section 50, and a fluid storage tank 60 is connected to the raw material tank 30. Then, the finally processed object to be treated is recovered from the drain portion 90.

The raw material tank 30 for storing the object to be processed and the branch block 40 downstream of the raw material tank 30 are installed via the piping section 81. The raw material tank 30 is a pressure-resistant container for storing an object to be processed, and is a container capable of maintaining the temperature and pressure at the time of circulation of the supercritical fluid described later. Further, the raw material tank 30 is provided with a stirrer 31, and the object to be treated and the supercritical fluid are mixed to form a dispersion.

In the supercritical fluid dispersion device 1 of the illustrated embodiment, the raw material tank 30 maintains the temperature and pressure conditions of the supercritical fluid. A warmer (heater) or the like is installed in the raw material tank 30. The pressure of the dispersion during flow is controlled through the supply pressure of the supercritical fluid supplied from the fluid storage tank 60 by the pressure pump 61. A check valve 70 and a switching valve 71 are installed in the piping section 81. The backflow from the branch block 40 side to the raw material tank 30 side is regulated by the check valve 70 and the switching valve 71.

The pump section 50 is connected to the branch block 40 by a piping section 82. Further, the orifice homogenizer portion 10 is connected to the branch block 40 by the piping portion 83. Further, the orifice homogenizer portion 10 is connected to the raw material tank 30 by the piping portion 84. A piping portion 86 is provided on the drain portion 90 side. Further, as shown in the figure, switching valves 72, 73, 74 are connected to each piping section. Each switching valve regulates the flow path of the fluid during the operation of the pump unit 50. Each switching valve is a solenoid valve or a manual valve as appropriate. The piping portions 81, 82, 83, 84, 85, 86 are hollow pipe bodies having excellent heat retention and pressure resistance, and the dispersion generated by mixing the object to be treated and the supercritical fluid maintains the temperature and pressure. It flows while flowing.

Although the structure of the branch block 40 is not particularly limited, it is a member formed of a pressure-resistant material such as metal and having a T-shaped flow path formed inside. Alternatively, the branch block 40 may be a known three-way valve or the like.

The pump unit 50 includes a piston 51 in the structure, and is generally called a piston pump. When the piston 51 is retracted (see FIG. 3 below), the dispersion generated by the mixing of the object to be processed and the supercritical fluid flows into the housing 52 of the pump portion 50. When the piston 51 moves forward (see FIG. 4 below), the dispersion of the object to be processed and the supercritical fluid is discharged from the pump section 50 and flows into the orifice homogenizer section 10. The forward and backward movements of the piston 51 are controlled by hydraulic drive, a servomotor or the like. The dispersion of the object to be treated and the supercritical fluid passes through the orifice homogenizer portion 10 and then flows into the raw material tank 30.

A fluid storage tank 60 for storing supercritical fluid is installed upstream of the raw material tank 30, and is connected by a piping portion 85. The pressure feeding pump 61 for pumping the supercritical fluid is installed in the piping portion 85, and the supercritical fluid is supplied from the fluid storage tank 60 to the raw material tank 30.

The dispersion of the object to be treated and the supercritical fluid that has passed through the orifice homogenizer portion 10 and has been miniaturized (pulverized) finally flows out from the drain portion 90 to the outside of the supercritical fluid dispersion device 1.

The structure of the orifice homogenizer portion 10 will be described with reference to the vertical sectional view of the main portion of FIG. 2 and the cross-sectional view of the main portion of FIG. The cross section taken along the line AA of FIG. 2 is shown in FIG. 3A, the cross section taken along the line BB of FIG. 2 is shown in FIG. 3B, and the cross section taken along the line CC of FIG. 2 is shown in FIG. 3 (c).

The orifice homogenizer portion 10 is formed by a first block 21, a second block 22, and a third block 23 interposed between the first block 21 and the second block 22. In the first block 21, a plurality of inflow side flow path portions 11 and 12 are formed (see FIGS. 2 and 3A). Further, also in the second block 22, a plurality of outflow side flow path portions 18 and 19 are formed.

The first gap portion 14 is intentionally formed on the joint surface between the first block 21 and the third block 23. The first gap portion 14 serves as a gathering portion 13 that singly aggregates a plurality of inflow side flow path portions 11 and 12 (see FIGS. 2 and 3 (b)). The downstream side of the collecting portion 13 (first gap portion 14) becomes the third block 23, and the orifice flow path portion 15 is formed in the third block 23 (see FIGS. 2 and 3 (c)).

Also on the downstream side of the orifice flow path portion 15, the second gap portion 16 is intentionally formed on the joint surface between the third block 23 and the second block 22. The second gap 16 serves as a branch 17 that branches the orifice flow path 15 and connects to a plurality of outflow side flow paths 18 and 19.

The inner diameters (D1) of the inflow side flow paths 11 and 12 and the outflow side flow paths 18 and 19 are the same as each other, and are formed larger than the inner diameter (D2) of the orifice flow path portion 15. Specifically, the inner diameter (D1) is 5 to 7 times the inner diameter (D2). Further, the distance (D3) of the first gap portion 14 is defined in the same manner as the inner diameter (D1). Therefore, the orifice flow path portion 15 is a small diameter flow path portion.

Next, the operation when the orifice homogenizer portion 10 is used will be described. The dispersion (pumping fluid) in which the object to be treated is dispersed in the supercritical fluid invades the collecting portion 13 (first void portion 14) via the inflow side flow path portions 11 and 12. Here, since the orifice flow path portion 15 is narrower than the inflow side flow path portions 11 and 12, the flow rate of the dispersion is reduced. Then, a pressure change of the dispersion (pumping fluid) occurs, and the dispersions flowing in from the respective inflow side flow paths collide with each other at the collecting portion 13. The objects to be treated in the dispersion at this time are crushed by the energy at the time of collision. In this way, each time the dispersion flows from the inflow side flow path portions 11 and 12 to the orifice flow path portion 15, the objects to be processed in the dispersion proceed to collide with each other, and as a result, the dispersion is crushed.

There are two inflow side flow paths and two inflow side flow paths in the figure. Of course, the number of inflow side flow paths and inflow side flow paths is 1 or more. However, in order to promote collision of the object to be processed in the dispersion, it is more desirable that the number of formed inflow side flow paths and inflow side flow paths is 2 or more. The illustrated orifice homogenizer portion 10 has a symmetrical shape on both the inflow side and the outflow side. Therefore, for convenience of explanation, the inflow side and the outflow side are used. Since the inflow side and the outflow side are symmetrical, the orifice homogenizer portion 10 can function in the inflow from any direction. Therefore, the dispersion may flow in from the outflow side flow paths 18 and 19, pass through the orifice flow path portion 15, and flow out from the inflow side flow paths 11 and 12.

From this, the supercritical fluid dispersion method of the present invention will be described using the supercritical fluid dispersion device 1 of the first embodiment. First, the object to be treated is dispersed in the supercritical fluid to become a "first dispersion" ("first supercritical fluid dispersion step"). Dispersion is performed in the raw material tank 30.

The object to be treated to be miniaturized is a wide variety of substances such as cellulose, graphite, graphene, carbon nanotubes, and composite metal oxides (crystals such as spinel and perovskite). By reducing the size through collisions between the objects to be processed, uniform dispersibility when mixed with a resin or the like after the fact is enhanced. Therefore, the performance of the material is expected to improve.

The supercritical fluid used in this dispersion method is carbon dioxide or water. In particular, carbon dioxide is preferable as a supercritical fluid because it vaporizes at normal temperature and pressure. In addition, although it is a polar molecule, its reactivity with polarity is weaker than that of water. When the supercritical fluid is carbon dioxide, only carbon dioxide evaporates at room temperature and normal pressure after being released from the drain portion 90. Therefore, separation after dispersion is extremely easy.

Here, the supercritical fluid is a fluid in which a liquid and a gas cannot be distinguished due to the temperature and pressure conditions peculiar to each substance. Specifically, the critical temperature of carbon dioxide is 304.1K, the critical pressure is 7.38MPa, the critical temperature of water is 647.3K, the critical pressure is 22.12MPa, and the critical temperature of ethane is 305.3K. The critical pressure is 4.87 MPa, the critical temperature of propane is 369.8 K, and the critical pressure is 4.25 MPa.

The supercritical fluid has high fluidity as compared with water, an organic solvent, etc. in a normal state. From this, it is expected that the viscosity of the first dispersion after mixing the object to be treated will decrease. Therefore, it is expected to reduce the resistance at the time of pressure feeding in the piping portion, particularly to the orifice homogenizer portion 10 having the small diameter flow path portion.

In addition to carbon dioxide and water, organic molecules such as ethane, propane, and ethylene can be used as the supercritical fluid. Carbon dioxide and water are polar molecules. Therefore, while the treatment is continued in the supercritical fluid dispersion device 1, the object to be treated may be attacked (reacted) by polar molecules depending on the supercritical conditions. In contrast, ethane, propane and ethylene are non-polar molecules. Therefore, even if the supercritical condition persists, the reactivity with the object to be treated is poor. Therefore, the type of supercritical fluid is selected in consideration of the properties of the object to be treated.

The first dispersion is pressurized and supplied to the orifice homogenizer portion 10 having the small diameter flow path portion. The pressurization is supplied by the pressing force of the piston 51 in the pump unit 50. The first dispersion flows into the orifice homogenizer section 10 and passes through the orifice homogenizer section 10. Here, as described above, the object to be treated in the first dispersion is miniaturized more than the initial state due to the impact energy when it collides in the flow path of the orifice homogenizer portion 10. In this way, the first dispersion passes through the orifice homogenizer portion 10 to obtain a "second dispersion" ("second supercritical fluid dispersion step"). The second dispersion is a dispersion in which the miniaturization of the object to be treated has progressed due to the reduction of the molecular chain length, the collapse of the crystal structure, and the like as compared with the first dispersion.

After the second supercritical fluid dispersion step, the second dispersion is discharged from the drain portion 90 via the piping portion 86. When carbon dioxide is used as the supercritical fluid, the supercritical fluid of carbon dioxide is easily removed by evaporation from the second dispersion released to the drain portion 90. As a result, microproducts of the object to be treated are isolated (“isolation step”). When water is used as the supercritical fluid, an evaporator (not shown) or the like is separately equipped in the drain portion 90 in order to isolate microparticles of the object to be treated. When ethane, propane, ethylene and the like are supercritical fluids, since they are flammable gases at room temperature and normal pressure, a dedicated recovery device (not shown) or the like is separately equipped in the drain portion 90.

The isolation step is a step added when separating the micronized object to be treated (micronized product) from the solvent of the supercritical fluid. For example, in a state where a cellulose object to be treated and water of a supercritical fluid are mixed, when it is not necessary to separate the micromaterials even after miniaturization, that is, when a moist mixed state is desired, isolation is performed. The process is omitted.

The fluid path in the supercritical fluid dispersion device 1 of the first embodiment will be described with reference to the schematic explanatory views of FIGS. 4 and 5. First, the piston 51 of the pump unit 50 retracts (in the direction of the white arrow in FIG. 4), and the inside of the housing 52 is depressurized. Therefore, the first dispersion in the raw material tank 30 flows into the housing 52 of the pump section 50 through the piping section 81, the branch block 40, and the piping section 82 (see FIG. 4). At this time, since the flow direction of the first dispersion is the forward flow direction from the raw material tank 30 to the branch block 40, the check valve 70 and the switching valve 71 in the valve open state can pass through.

Next, the piston 51 of the pump section 50 advances (in the direction of the white arrow in FIG. 5), and the first dispersion in the housing 52 is extruded from the pump section 50. Then, the first dispersion passes through the piping section 82, the branch block 40, and the piping section 83 and flows into the orifice homogenizer section 10. Due to the push output of the pump unit 50, the first dispersion can pass through the orifice homogenizer unit 10 provided with the small diameter flow path portion (see FIG. 5).

As the first dispersion passes through the orifice homogenizer portion 10, it becomes smaller and becomes the second dispersion. Then, the second dispersion flows into the raw material tank 30 via the piping portion 84 and the switching valve 73. Subsequently, the first dispersion (second dispersion after mixing) in the raw material tank 30 flows into the housing 52 of the pump unit 50 again (see FIG. 4), and the first dispersion is caused by the push output of the pump unit 50. The dispersion (second dispersion after mixing) passes through the orifice homogenizer portion 10 (see FIG. 5).

In this way, after the first dispersion passes through the orifice homogenizer section 10, the first dispersion passes through the orifice homogenizer section 10 again to prepare the second dispersion. That is, the number of collisions between the objects to be processed in the orifice homogenizer portion 10 increases, and the miniaturization is further promoted. When the miniaturization of the object to be processed has progressed sufficiently, the second dispersion is discharged from the drain portion 90 at the tip of the piping portion 86 (see the broken line arrow in FIG. 5).

Further, the fluid path in the supercritical fluid dispersion device 2 of the second embodiment will be described with reference to the schematic explanatory views of FIGS. 6, 7, and 8. In the supercritical fluid dispersion device 2 of the second embodiment, an intermediate tank 35 is installed in the piping portion 84. Since other configurations are the same as those of the supercritical fluid dispersion device 1 of the first embodiment, the description thereof will be omitted.

First, the piston 51 of the pump unit 50 retracts to reduce the pressure inside the housing 52. Therefore, the first dispersion in the raw material tank 30 flows into the housing 52 of the pump section 50 through the piping section 81, the branch block 40, and the piping section 82 (see FIG. 6). At this time, since the flow direction of the first dispersion is the forward flow direction, the check valve 70 and the switching valve 71 in the valve open state can pass through.

Next, the piston 51 of the pump unit 50 advances and the first dispersion in the housing 52 is extruded from the pump unit 50. Then, the first dispersion passes through the piping section 82, the branch block 40, and the piping section 83 and flows into the orifice homogenizer section 10. Due to the push output of the pump unit 50, the first dispersion can pass through the orifice homogenizer unit 10 provided with the small diameter flow path portion (see FIG. 6). As the second dispersion passes through the orifice homogenizer portion 10, it becomes smaller and becomes the second dispersion. Then, in the supercritical fluid dispersion device 2 of the second embodiment, the second dispersion flows into the intermediate tank 35.

Since the intermediate tank 35 is provided separately from the raw material tank 30, mixing of the second dispersion with advanced miniaturization and the object to be treated in the raw material tank 30 before treatment is avoided. In the case of the supercritical fluid dispersion device 2 of the second embodiment, the method by batch processing is preferable. The intermediate tank 35 is appropriately provided with a warmer, a pressurizer, and the like for maintaining the critical temperature and pressure of the supercritical fluid (not shown).

Subsequently, due to the retreat of the piston 51 in the pump portion 50, the inside of the housing 52 becomes a negative pressure. Therefore, the second dispersion in the intermediate tank 35 flows in from the outflow side flow path portions 18 and 19 of the orifice homogenizer portion 10 and outflows from the inflow side flow path portions 11 and 12, contrary to FIG. Then, it passes through the piping section 83, the branch block 40, and the piping section 82 and flows into the housing 52 of the pump section 50 (see FIG. 8). After that, due to the push output of the piston 51 of the pump section 50, the second dispersion passes through the orifice homogenizer section 10 again (see FIG. 6).

In the supercritical fluid dispersion device 2 of the second embodiment, after the first dispersion has passed through the orifice homogenizer section 10, it is temporarily stored in the intermediate tank 35 and again passes through the orifice homogenizer section 10 in the reverse direction. Two dispersions are prepared. In particular, since the orifice homogenizer portion 10 has a common structure on the upstream side and the downstream side, it can be used to reverse the direction of such flow. Of course, it is also possible to return the second dispersion stored in the intermediate tank 35 to the raw material tank 30 due to the configuration of the piping portion.

In the supercritical fluid dispersion method of the present invention, by using a supercritical fluid as a solvent, high fluidity can be ensured and the object to be treated can be dispersed, flowed and pulverized. For this reason, the fluidity in the flow path becomes good, and it is promising that the load during the conventional pumping can be reduced.

1,2 Supercritical fluid disperser 10 Orifice homogenizer part 11, 12 Inflow side flow path part 13 Assembly part 14 First gap part 15 Orifice flow path part 16 Second void part 17 Branch part 18, 19 Outflow side flow path part 21 1st block 22 2nd block 23 3rd block 30 Raw material tank 35 Intermediate tank 40 Branch block 50 Pump part 51 Piston 52 Housing 60 Fluid storage tank 61 Pressure feed pump 70 Check valve 71, 72, 73, 74 Switching valve 81, 82 , 83, 84, 85 Piping section 90 Drain section

Claims (5)

The first supercritical fluid dispersion step of dispersing the object to be treated in the supercritical fluid to obtain the first dispersion, and
A second supercritical fluid dispersion step of pressurizing and supplying the first dispersion to an orifice homogenizer portion provided with a small-diameter flow path portion to miniaturize the object to be treated in the first dispersion to obtain a second dispersion. When,
A supercritical fluid dispersion method comprising. In the second supercritical fluid dispersion step, after the first dispersion passes through the orifice homogenizer portion, the first dispersion after passing passes through the orifice homogenizer portion again repeatedly, and the second dispersion The supercritical fluid dispersion method according to claim 1, wherein the above is prepared. The supercritical according to claim 1 or 2, wherein after the second supercritical fluid dispersion step, an isolation step of removing the supercritical fluid from the second dispersion and isolating microparticles of the object to be treated is added. Fluid dispersion method. The supercritical fluid dispersion method according to any one of claims 1 to 3, wherein the supercritical fluid is a supercritical fluid of carbon dioxide. The orifice homogenizer portion
With multiple inflow side flow paths
With multiple outflow side flow paths
A gathering part that collects the plurality of inflow side flow path parts in a single unit
An orifice flow path portion connected to the downstream of the gathering portion and
A branching portion connected to the downstream of the orifice flow path portion, branching the orifice flow path portion, and connecting to the plurality of outflow side flow path portions.
The supercritical fluid dispersion method according to any one of claims 1 to 4.

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