JP2014104405A - Apparatus and method for dispersing aggregate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for dispersing an aggregate where dispersion processing that a processing object consisting of the aggregate of minute elements is dispersed can be easily performed with excellent processing efficiency while ensuring processing quality.SOLUTION: The droplets of a slurry 33 where an aggregate 35 aggregated with minute elements such as scaly solid particles and the like of carbon nanotubes and mica is mixed with a liquid are formed by the jet stream of a gas using a jet nozzle 7 and accelerated. A dispersion 35b is separated from the surface 35a of the aggregate 35 by shear force acting to the aggregate 35 due to speed difference between the gas and the aggregate 35 in the jet stream in a droplet acceleration step and dispersed to an aggregate having a smaller size than before dispersion processing.

Description

  The present invention relates to an agglomerate dispersion apparatus and a dispersion method for performing a dispersion treatment for dispersing an object to be processed composed of agglomerates of minute elements.

  In recent years, in the field of new material development, fine materials using nanotechnology such as carbon nanotubes have attracted attention, and application to many industrial fields is expected. Such a minute material is produced in the form of an aggregate in which many minute elements are aggregated during the production process. For this reason, when applied to an actual product, it is necessary to obtain an intermediate product in which minute elements in an aggregated state are uniformly dispersed and contained in a medium such as a liquid. As a technique for such a dispersion treatment, a method of stirring an aggregate together with a solvent has been proposed (see Patent Documents 1 and 2). In the example shown in Patent Document 1, the stirrer is rotated at a high speed in a container containing the aggregate and the solvent so as to stir at high speed. Moreover, in the example shown in patent document 2, the example using the stirring blade for generating an upflow in a container and the stirring blade for shearing an aggregate is shown.

JP 2008-195563 A JP 2011-230995 A

  However, the prior art including the prior art shown in the above-mentioned patent document examples has the following problems in terms of processing quality and processing efficiency. That is, in the prior art, the dispersion mechanism is mechanical stirring, so that when a minute element such as a carbon nanotube is targeted, a sufficient dispersion effect cannot always be obtained, and it is difficult to ensure processing quality. Met. As a result of this, it is necessary to set complicated processing steps in the process of distributed processing, and the desired processing efficiency cannot be realized. Such a problem is common not only in carbon nanotubes but also in the dispersion treatment of aggregates in which minute scale-like solid particles are aggregated.

  Accordingly, the present invention provides an agglomerate dispersion apparatus and dispersion method that can easily carry out a dispersion process for dispersing a treatment object made of agglomerates of microelements with good treatment efficiency while ensuring treatment quality. For the purpose.

  The agglomerate dispersion apparatus according to the present invention is an agglomerate dispersion apparatus that performs a dispersion process for dispersing a treatment object made of agglomerates of microelements, and supplies a slurry-like substance in which the treatment object is mixed with a liquid. And a slurry accelerating means for accelerating the slurry-like substance into droplets by means of a gas jet, and shearing acting on the aggregates due to a speed difference between the gas and the aggregates in the jet The microelements are separated from the aggregate by force and dispersed into an aggregate having a smaller size than before the dispersion treatment.

  The method for dispersing an aggregate according to the present invention is a method for dispersing an aggregate that performs a dispersion process for dispersing an object to be processed composed of aggregates of microelements, and supplying a slurry-like substance in which the object to be processed is mixed with a liquid A slurry-like material supplying step, and a droplet accelerating step for accelerating the slurry-like material into droplets by a gas jet, and in the droplet acceleration step, the velocity of the gas and the aggregate in the jet Due to the shearing force acting on the aggregate due to the difference, the microelements are separated from the aggregate and dispersed into the aggregate having a smaller size than before the dispersion treatment.

  According to the present invention, in a droplet accelerating step of accelerating a slurry-like substance obtained by mixing an object to be processed with a liquid into droplets by a gas jet, the slurry acts on the aggregate by a speed difference between the gas and the aggregate in the jet. By using a method that separates microelements from aggregates by shearing force and disperses them into aggregates of a smaller size than before the dispersion process, dispersion processing that disperses the processing object consisting of aggregates of microelements is processed quality Can be easily performed with good processing efficiency while ensuring the above.

The block diagram which shows the structure of the dispersion apparatus of the aggregate of one embodiment of this invention Sectional drawing of the injection chamber used for the dispersion apparatus of the aggregate of one embodiment of this invention Sectional drawing of the jet nozzle used for the dispersion apparatus of the aggregate of one embodiment of this invention Form explanatory drawing of the processing target object in the dispersion method of the aggregate of one embodiment of this invention Process explanatory drawing of the dispersion method of the aggregate of one embodiment of this invention The image figure which shows the example of a processing result by the dispersion | distribution method of the aggregate of one embodiment of this invention The image figure which shows the example of a processing result by the dispersion | distribution method of the aggregate of one embodiment of this invention

  Next, embodiments of the present invention will be described with reference to the drawings. First, with reference to FIG. 1, the overall configuration of the aggregate dispersing apparatus will be described. The agglomerate dispersing apparatus 1 has a function of performing a dispersion process for dispersing a processing object made of agglomerates of microelements. In the present embodiment, aggregates are formed in a state in which minute elements are entangled or laminated, such as carbon nanotubes or mica (mica) scale-like solid particles, and a method such as mechanical stirring is effective. An example is shown in which a substance that is difficult to be dispersed is treated.

  In FIG. 1, an aggregate dispersion device 1 includes a slurry storage unit 2 that stores a slurry-like substance (hereinafter simply referred to as “slurry”) containing an aggregate to be processed in a liquid. The slurry stored in the slurry storage unit 2 is supplied to a jet nozzle 7 attached to the upper end of the injection chamber 6. Therefore, the slurry storage part 2 is a slurry-like substance supply means for supplying a slurry-like substance in which a processing target is mixed with a liquid.

  The slurry is microdropletized and accelerated at high speed by the gas flow generated by supplying air from the air supply source 5 to the jet nozzle 7. The air supply source 5 and the jet nozzle 7 constitute droplet accelerating means for accelerating the slurry substance into droplets by a gas jet. Thereby, the agglomerates of the microelements in the slurry are dispersed into smaller-sized agglomerates and collected in the collection tank 9. The recovered slurry after dispersion treatment is subjected to dispersion treatment multiple times as necessary. An exhaust unit 8 is attached to the injection chamber 6 and collects mist-like exhaust generated in the injection chamber 6.

  Next, the configuration of the injection chamber 6 disposed in the dispersion processing unit 4 will be described with reference to FIG. The injection chamber 6 is a vertical substantially cylindrical processing container that is divided into an upper part 61, an intermediate part 62, and a lower part 63. The inside of the injection chamber 6 includes an injection space 6 a for injecting a jet flow from the jet nozzle 7. It has become. The upper part 61 and the intermediate part 62, and the intermediate part 62 and the lower part 63 are connected via annular joints 69b and 69c, respectively.

  A nozzle holder 68 is coupled to a nozzle mounting portion 61a provided by narrowing the top of the upper portion 61 via an annular joint 69a, and the jet nozzle 7 is mounted on the nozzle holder 68 from above. With such a configuration, the upper portion 61, the intermediate portion 62, and the lower portion 63 can be easily disassembled as needed for internal component replacement, and the jet nozzle 7 can be easily attached and detached. ing,

  An air supply pipe 70 and a slurry supply pipe 71 are led to the jet nozzle 7, and driving air and a dispersion target for generating a gas flow in the jet nozzle 7 by the air supply pipe 70 and the slurry supply pipe 71. The slurry 33 containing the aggregate 35 is supplied (see FIG. 5). A flange 63b extending laterally is provided on the outer surface of the drainage part 63a provided by narrowing the bottom of the lower part 63, and the recovery tank 9 is connected to the flange 63b via an annular joint 69d. Yes.

  Inside the drainage part 63a is a drainage hole 63c, and slurry containing aggregates that have been dispersed by the injection chamber 6 flows into and is stored in the recovery tank 9 via the drainage hole 63c. . By removing the collection tank 9, the treated slurry 33 stored inside is collected. A branch pipe 62a that forms an exhaust suction port 62b projects from the outer surface of the intermediate section 62, and the exhaust unit 8 is connected to the branch pipe 62a. By operating the exhaust unit 8, the inside of the injection chamber 6 is sucked through the exhaust suction port 62 b and exhausted by the exhaust unit 8.

  Next, the structure of the jet nozzle 7 will be described with reference to FIG. As shown in FIG. 3, the jet nozzle 7 is mainly composed of a cylindrical nozzle body 7a, and an internal flow path hole 31 is formed through the nozzle body 7a in the longitudinal direction. The upstream side of the internal flow path hole 31 is an introduction part 31a to which the air supply pipe 10 is connected and compressed air (arrow a) that is a compressed gas is introduced. On the downstream side of the introduction part 31a, a convergent part 31b in which the flow path diameter of the internal flow path hole 31 is narrowed along the flow direction, a throat part 31c in which the flow path diameter is narrowed the smallest, and a divergent in which the flow path diameter increases. The part 31d and the accelerated cooling part 31e whose flow path diameter gradually increases are sequentially provided in the flow direction of the compressed air. The opening where the accelerated cooling part 31e reaches the end of the nozzle body part 7a serves as an injection port 7b for injecting a jet flow containing minute droplets.

  The jet nozzle 7 configured as described above forms a Laval nozzle having a convergent portion 31b, a throat portion 31c, and a divergent portion 31d. The nozzle body 7a is formed of a resin such as PTFE resin or a metal, and is manufactured by integrally molding one that is integrally formed or appropriately divided. The diameter of the throat portion 31c is appropriately set, for example, from a range of 3 to 10 mm, and the distance from the throat portion 31c to the injection port 7b is set to a distance sufficient for accelerating the compressed air in a range of 100 to 300 mm, for example. .

  That is, after the pressure is adjusted so that the throat portion 31c has a high speed of about the speed of sound, the compressed air is supplied to the convergent portion 31b at a subsonic speed (for example, about 50 m / sec) and accelerated by the convergent portion 31b. The sound velocity (about 330 m / sec) is obtained at the throat portion 31c, and further accelerated by the divergent portion 31d, for example, to a supersonic velocity of about 400 to 500 m / sec. A slurry supply pipe 32 that discharges the slurry 33 containing aggregates in the same direction as the flow of compressed air is provided on the upstream side of the throat portion 31c. Here, the slurry 33 is supplied through the slurry supply pipe 11 in a predetermined amount set in advance. The supplied slurry 33 is discharged from the discharge port at the tip of the slurry supply pipe 32 to become a minute droplet 34, and flows to the downstream side together with the compressed air at a high speed.

  The discharge port of the slurry supply pipe 32 is located in the vicinity of the throat portion 31c and away from the inner wall surface of the internal flow path hole 31, for example, five times the inner diameter of the throat portion 31c in the upstream direction and the downstream direction from the center of the throat portion 31c. It is arrange | positioned in the discharge port arrangement | positioning range which is less than the range of length of this. As described above, by disposing the discharge port of the slurry supply pipe 32 in the vicinity of the throat portion 31c away from the inner wall surface of the nozzle main body portion 7a, the droplet 34 in which the discharged slurry 33 is atomized becomes the nozzle main body portion 7a. It becomes difficult to be affected by the boundary layer region formed on the inner wall surface of the liquid, and thus the speed reduction of the droplet 34 can be suppressed and the acceleration can be sufficiently accelerated.

  The jet acceleration process in the jet nozzle 7 will be described. The flow of compressed air supplied to the introduction portion 31a as drive air at a set pressure (for example, 0.5 MPa) is first accelerated by the convergent portion 31b (arrow b), and passes through the throat portion 31c at a flow velocity about the speed of sound. Then, by moving from the throat portion 31c into the divergent portion 31d, the pressure is reduced and further accelerated (arrow c). Then, the droplet 34 discharged from the discharge port of the slurry supply pipe 32 and atomized by the flow of compressed air flows at a high speed to the downstream side while being accelerated in the accelerating cooling unit 31e that gradually expands (arrow d), It is ejected from the ejection port 7 b of the jet nozzle 7. The degree of diameter expansion in the accelerated cooling portion 31e is determined in consideration of the thickness of the boundary layer region formed near the inner wall surface of the internal flow path hole 31.

  In general, in the flow of fluid in a circular pipe, a boundary layer in which the flow state changes near the inner wall surface of the pipe, and the flow velocity decreases in this boundary layer region. In the case of a flow in a circular pipe having a constant pipe inner diameter, the boundary layer region expands in the vicinity of the pipe outlet, and as a result, the flow velocity decreases near the center of the flow. On the other hand, by providing the acceleration cooling part 31e that gradually expands in the flow direction in consideration of the boundary layer region, it is possible to suppress the influence of a decrease in the flow velocity in the boundary layer region, and to increase the speed even in the vicinity of the injection port 7b. The flow can be secured in a wide range. That is, the droplet accelerating means configured as described above has a function of accelerating and ejecting the droplet 34 of the slurry 33 at a predetermined speed that is at least one time the speed of sound.

  In the present embodiment, in the jet flow obtained by accelerating the droplets 34 of the slurry 33 including the aggregates 35 of the microelements of the processing target with the gas, the shear acting on the aggregates due to the speed difference between the gas and the aggregates 35. The microelements are sequentially separated from the surface of the aggregate 35 by the force, and are dispersed in an aggregate having a size smaller than that before the dispersion treatment (see FIG. 5).

  The jet chamber 6 can use not only the above-described Laval nozzle type jet nozzle 7 but also a general two-fluid nozzle type jet nozzle as the droplet accelerating means. These jet nozzles are selectively used depending on the degree of dispersion difficulty of the material to be dispersed and the desired dispersion mode, that is, the required uniformity of the particle size distribution and the degree of damage allowed to the fine particles after the dispersion treatment. It is attached to. Here, the degree of dispersion difficulty is not a strictly defined concept, but the magnitude of the binding force of the target microelements, that is, the magnitude of the physical force required to separate the microelements from the aggregate by physical means Should be considered as meaning. This degree of distribution difficulty is determined from the result of actually trying the distribution process individually.

  The Laval nozzle type jet nozzle 7 is used when the dispersion speed determined by the type of aggregate to be dispersed and the predetermined speed defined according to the desired dispersion mode are equal to or higher than the sound speed. That is, when the dispersion difficulty of the aggregates to be dispersed is high, the jet nozzle 7 shown in FIG. 3 is selectively used. On the other hand, when the predetermined speed required for accelerating the droplet 34 is a speed range lower than the sonic speed, a general two-fluid nozzle type jet nozzle can be appropriately selected.

  As such a two-fluid nozzle type jet nozzle, it is possible to eject fine droplets generated by supplying a slurry containing aggregates into a gas flow generated by narrowing the flow path of driving air. Any type of two-fluid nozzle may be used as long as the droplet can be accelerated to a predetermined speed according to the dispersion difficulty of the substance to be dispersed and the desired degree of dispersion. .

  Next, with reference to FIG. 4, the form of the aggregate 35 used as the process target in this Embodiment is demonstrated. FIG. 4A shows an example in which the processing target contained in the slurry 33 is a fibrous aggregate 35A in which carbon nanotubes are aggregated. In FIG. 4 (a), the aggregate 35A exists in a state where fine fibrous carbon nanotubes 36 are irregularly superimposed or entangled to be aggregated, and uniform by simple mechanical operation such as stirring in a liquid. Difficult to disperse. That is, in the example shown in FIG. 4A, the microelements are carbon nanotubes 36, and the treatment target is a fibrous aggregate 35A in which the carbon nanotubes 36 are aggregated.

  FIG. 4B shows an example in which the processing target contained in the slurry 33 is a fibrous aggregate 35B in which scale-like solid particles of mica (mica) are aggregated. In FIG. 4B, the aggregate 35B exists in a state where the mica (mica) scale-like solid particles 37 are laminated and aggregated, and similarly, it is difficult to uniformly disperse by a simple mechanical operation. . That is, in the example shown in FIG. 4B, the microelement is a scale-like solid particle, and the processing target is a solid aggregate 35B in which the solid particles are aggregated.

  The agglomerates 35 contained in the slurry 33 are not limited to the agglomerates 35A and 35B described above, and may be aggregates of minute elements that are difficult to disperse uniformly by a simple mechanical operation. Various materials such as metal powders, intermetallic compound powders, ceramic powders such as oxides, carbides, and nitrides, organic compounds, and mixed powders thereof can be treated. The aggregated state also varies depending on the substance, and the aggregate includes not only the form in which the flakes are simply laminated, but also a substance that is solidified so as to be partially peelable from the surface.

  The liquid used for the slurry 33 is water, hydrocarbons, alcohols, ethers, ketones, esters, carboxylic acids, phenols, nitrogen-containing compounds, sulfur-containing compounds, fluorine compounds, and inorganic solvents. It is preferable to use what is conventionally used for dispersion | distribution of an aggregate like these, and you may mix these as needed. Furthermore, you may mix | blend a well-known additive in order to maintain the dispersion state of the microelement after a dispersion process. Known additives include, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, polymer surfactants, silicone surfactants, and fluorine surfactants. It is preferable to add a necessary amount of an additive that can achieve the above-mentioned purpose.

  Next, with reference to FIG. 5, an aggregate dispersion method that is performed using the aggregate dispersion apparatus 1 will be described. First, prior to the execution of the process, a slurry 33 is prepared by previously mixing a processing object including the aggregate 35A and the aggregate 35B with a liquid, and the slurry 33 stored in the slurry storage unit 2 is supplied to the jet nozzle 7 (slurry). Process of supplying a solid substance). Thereby, as shown in FIG. 5A, the slurry 33 is discharged from the slurry supply pipe 32 in the vicinity of the throat portion 31c.

  At this time, driving air is supplied to the internal flow path hole 31 at a set pressure (for example, 0.5 MPa), thereby being accelerated by the convergent portion 31b downstream from the internal flow path hole 31 (arrows). e) Passes through the throat portion 31c in the form of a jet having a velocity about the speed of sound. Then, as shown in FIG. 5B, the slurry 33 discharged from the slurry supply pipe 32 becomes a droplet 34 by the jet, and the jet including the droplet 34 further passes through the divergent portion 31d from the throat portion 31c. Move further downstream. In this process, the pressure decreases, and the droplet 34 is further accelerated (arrows f and g). That is, here, the slurry 33 is made into droplets by a gas jet and accelerated (droplet acceleration step).

  In this droplet accelerating step, as shown in FIG. 5C, the droplet 34 is accelerated by the gas flow (flow velocity va) in the jet and flows downstream with the aggregate 35 at the flow velocity vd. At this time, since the flow velocity va of the gas is much larger than the flow velocity vd of the droplet 34, the surface 35a of the aggregate 35 in the vicinity of the surface of the droplet 34, as shown in FIG. The fluid force resulting from the speed difference (va−vd) acts. This fluid force separates the dispersion 34b, that is, an aggregate having a size smaller than that before the dispersion treatment, from the surface 34a of the droplet 34. This separation action separates microelements (carbon nanotubes 36 or solid particles 37) in the vicinity of the surface 34a from the aggregate 34 by a shearing force acting on the aggregate 34 due to the difference in velocity between the gas and the aggregate 35 in the jet. Is done.

  FIG. 6 shows the effect of the dispersion treatment performed by the above-described method using the fibrous aggregate 35A in which carbon nanotubes are aggregated as a treatment target. FIGS. 6A, 6B, and 6C are microscopic images showing states before processing, after one pass processing, and after five pass processing, respectively, and (A) and (B) are different for the same processing target. An image taken at a magnification is shown. As can be seen from these images, the degree of dispersion from the aggregate 35A to the carbon nanotubes 36 increases as the number of processing passes increases.

  FIG. 7 shows the effect of the dispersion treatment on the aggregate 35B in which the mica (mica) scale-like solid particles are aggregated. FIGS. 7A, 7B, and 7C are microscopic images showing the unprocessed product, the state after one pass processing, and the state after the five pass processing, respectively. FIGS. 7A and 7B are the same processing targets. Images taken at different magnifications are shown. Similarly, in this example, the degree of dispersion from the aggregate 35B to the solid particles 37 is improved as the number of treatment passes is increased.

  As described above, in the dispersion apparatus and dispersion method for aggregates shown in the present embodiment, in the droplet acceleration step of accelerating the slurry-like substance obtained by mixing the object to be processed into liquid droplets by a gas jet, The microelements are separated from the aggregates by the shearing force acting on the aggregates due to the difference in velocity between the gas and the aggregates in the jet, and dispersed into aggregates having a size smaller than that before the dispersion treatment. Thereby, the dispersion | distribution process which disperse | distributes the process target consisting of the aggregate of a microelement can be simply performed by favorable process efficiency, ensuring process quality.

  The agglomerate dispersion apparatus and dispersion method of the present invention have the advantage that a dispersion process for dispersing a processing object consisting of agglomerates of microelements can be easily performed with good treatment efficiency while ensuring treatment quality. And is useful in the field of dispersing aggregates of microelements such as carbon nanotubes.

DESCRIPTION OF SYMBOLS 1 Aggregate dispersion apparatus 2 Slurry storage part 4 Dispersion process part 5 Air supply source 6 Injection chamber 7 Jet nozzle 9 Recovery tank 33 Slurry 34 Droplet 35, 35A, 35B Aggregate 36 Carbon nanotube 37 Solid particle

Claims (6)

An agglomerate dispersion apparatus that performs a dispersion process for dispersing an object to be processed consisting of agglomerates of microelements,
Slurry-like substance supply means for supplying a slurry-like substance in which the object to be treated is mixed with a liquid;
A droplet accelerating means for accelerating the slurry-like substance into droplets by a gas jet;
The microelements are separated from the aggregate by a shearing force acting on the aggregate due to a difference in velocity between the gas in the jet and the aggregate, and dispersed into an aggregate having a size smaller than that before the dispersion treatment. Aggregate dispersion device.   2. The aggregate dispersion apparatus according to claim 1, wherein the microelements are carbon nanotubes, and the processing object is a fibrous aggregate in which carbon nanotubes are aggregated.     2. The aggregate dispersion apparatus according to claim 1, wherein the microelements are scale-like solid particles, and the processing object is a solid aggregate in which solid particles are aggregated. An agglomerate dispersion method for carrying out a dispersion process for dispersing an object to be processed consisting of agglomerates of microelements,
A slurry-like substance supplying step of supplying a slurry-like substance in which the object to be treated is mixed with a liquid;
A droplet accelerating step of accelerating the slurry-like substance by droplet formation by a gas jet,
In the droplet accelerating step, the microelements are separated from the aggregate by a shearing force acting on the aggregate due to the difference in velocity between the gas in the jet and the aggregate, and the aggregate has a smaller size than before the dispersion treatment. A method for dispersing an aggregate, characterized by being dispersed in a glass.   5. The method for dispersing aggregates according to claim 4, wherein the microelements are carbon nanotubes, and the object to be treated is a fibrous aggregate in which carbon nanotubes are aggregated.     5. The method for dispersing aggregates according to claim 4, wherein the microelements are scale-like solid particles, and the processing object is a solid aggregate in which solid particles are aggregated.