JP2011194366A - Method for manufacturing fine particle and apparatus for manufacturing fine particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing fine particles with high crystallinity by using a build-up method.SOLUTION: The method involves a bubble generation step of generating bubbles in a poor solvent with low solubility of a material of forming fine particles and a mixing step of mixing a solution in which the material of forming fine particles is dissolved and the poor solvent containing the bubbles, and fine particles are precipitated on the surfaces of the bubbles.

Description

  The present invention relates to a fine particle production method and a fine particle production apparatus, and more particularly to a fine particle production method and a fine particle production apparatus by crystal precipitation.

  Nano-sized fine particles are used as various functional materials because of their large surface area and low scattering. In addition, the cost of the fine-molding material can be reduced by producing hollow fine particles having cavities inside. One method for producing nano-sized fine particles is a build-up method. The build-up method is a method for precipitating fine particles by bringing a solution in which the fine particle forming material is dissolved in a solvent into contact with a poor solvent in which the fine particle forming material is difficult to dissolve.

  The build-up method is described in Patent Document 1. The fine particle production method described in Patent Document 1 includes a step of bringing a solution and a poor solvent into contact with an aggregating agent in a reaction channel when forming fine particles by a build-up method. Thereby, since fine particle formation and aggregate formation can be performed simultaneously, it is said that the manufacturing apparatus can be simplified.

  Further, methods for producing hollow microcapsules are described in Patent Document 2 and Non-Patent Document 1. Both methods for producing hollow microcapsules include a step of carrying out a polymerization reaction at the gas-liquid interface of fine bubbles dispersed in a liquid. As a result, a large number of hollow microcapsules can be manufactured at low cost.

JP 2009-227841 A JP 2007-21315 A

AIST press release, "Hollow microcapsules made from microbubbles", October 4, 2006

  However, in the conventional build-up method as described in Patent Document 1, the seed crystal is micro-sized, and nano-sized fine particles cannot be formed. Further, if precipitation is performed without using a seed crystal, the resulting fine particles have poor crystallinity, and therefore a crystal conversion step such as annealing is further required to improve the crystallinity.

  Further, the conventional method for producing hollow microcapsules described in Patent Document 2 is a method for producing microcapsules based on a polymerization reaction, and there has been no report on a method for producing microcapsules by a build-up method.

  In view of such circumstances, the present invention is to provide a method for producing nano-sized particles and hollow particles having good crystallinity and a production apparatus used therefor.

  The fine particle manufacturing method according to the first aspect of the present invention includes a bubble generation step of generating bubbles in a poor solvent having a low solubility of the fine particle forming material, a solution in which the fine particle forming material is dissolved, and the bubbles. And a mixing step of mixing the poor solvent contained therein, and the main feature is that the fine particles are precipitated on the surface of the bubbles.

  According to the above means, the fine crystal can be deposited on the surface of the bubble by using the bubble as a seed crystal. Thereby, since it can precipitate more slowly than the case where a crystal is precipitated in a liquid without seed crystals, fine particles with good crystallinity can be obtained.

  The fine particle production method according to the second aspect of the present invention is characterized in that, in addition to the first aspect, the method further includes a step of pulverizing the bubbles after the mixing step.

  Thereby, even if adjacent particles among the fine particles deposited on the surface of the bubbles form weak aggregates, the bubbles are crushed, and at the same time, the fine particles are crushed to be in a finely dispersed state. That is, very fine particles can be obtained.

  The fine particle production method according to the third aspect of the present invention is characterized in that, in the first or second aspect, the diameter of the bubbles is 50 nm to 10 μm.

  Thereby, fine particles with good crystallinity can be obtained in one process.

  The fine particle production method according to the fourth aspect of the present invention is characterized in that, in any one of the first to third aspects, the bubbles are cavities generated by an ultrasonic generator.

  Thereby, it is possible to obtain a simpler and better fine crystal in one process.

  The method for producing fine particles according to the fifth aspect of the present invention includes, in the first aspect, after the fine particles are deposited on the surface of the bubbles, the step of continuing the precipitation until the fine particles deposited on the entire surface of the bubbles are covered. Further, the main feature is to produce hollow fine particles.

  Thereby, hollow microparticles with high crystallinity can be obtained by the build-up method.

  The fine particle production apparatus according to the sixth aspect of the present invention includes a solution supply means for supplying a solution in which the fine particle component is dissolved, and a poor solvent for supplying a poor solvent having a low solubility of the fine particle component. A supply means; a bubble generator for generating bubbles in the poor solvent supplied from the poor solvent supply means; a solution introduction flow path for circulating the solution supplied from the solution supply means; A poor solvent introduction channel for circulating a poor solvent in which bubbles are generated by a bubble generator, a solution flowing out from the solution introduction channel, and a poor solvent flowing out from the poor solvent introduction channel A mixing portion for mixing the solution, a reaction channel for circulating the mixed solution of the solution and the poor solvent mixed in the mixing portion, and bubble pulverizing means for pulverizing bubbles in the mixed solution. Mainly provided It is characterized.

  By using this apparatus, it is possible to deposit crystals of the fine particles on the surface of the bubbles using the bubbles as seed crystals. Thereby, since it can precipitate more slowly than the case where a crystal is precipitated in a liquid without seed crystals, fine particles with good crystallinity can be obtained.

  The fine particle production apparatus according to the seventh aspect of the present invention is characterized in that, in addition to the sixth aspect, the bubble generator generates bubbles of 50 nm to 10 μm.

  Thereby, it is possible to obtain a simpler and better fine crystal in one process.

  The fine particle production apparatus according to the eighth aspect of the present invention is characterized in that, in the sixth or seventh aspect, the bubble generator is an ultrasonic generator.

  The fine particle production apparatus according to the ninth aspect of the present invention is characterized in that, in any of the sixth to eighth aspects, the bubble crushing means is an ultrasonic generator.

  According to the fine particle production method and fine particle production apparatus of the present invention, fine particles having good crystallinity can be produced by a built-up method.

It is a schematic perspective view which shows one Example of the fine particle manufacturing apparatus used for this invention. It is explanatory drawing explaining an example which provided five introduction paths in the fine particle manufacturing apparatus used for this invention. It is explanatory drawing of the condition at the time of bubble crushing. It is explanatory drawing of hollow particle preparation.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. Here, in the figure, portions indicated by the same symbols are portions corresponding to each other having the same function. In addition, in the present specification, when a numerical range is expressed using “˜”, upper and lower numerical values indicated by “˜” are also included in the numerical range.

<Particle production equipment>
An embodiment of a production apparatus used in the fine particle production method of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing an embodiment of a fine particle production apparatus used in the present invention.

  An example of producing organic pigment fine particles using an organic pigment as the fine particle forming material will be described. However, the production apparatus used in the present invention is not limited to the production of organic pigment fine particles. For example, inorganic pigment fine particles It can be widely applied to the production of silica particles, magnesium hydroxide particles and the like.

  As shown in FIG. 1, the fine particle production apparatus 10 of the present invention mainly includes an apparatus main body 12, a solution pipe 14 for flowing a solution L1 obtained by dissolving an organic pigment in a good solvent to the apparatus main body 12, and the good solvent. A poor solvent pipe 16 that flows the poor solvent L2 that is compatible and does not dissolve the organic pigment to the apparatus main body 12, and each supply means that supplies the solution L1 and the poor solvent L2 to the apparatus main body 12 through the respective pipes 14 and 16. 18, 20, a storage unit 50 that is disposed between the poor solvent supply unit 20 and the poor solvent pipe 16 and stores the poor solvent L <b> 2, and is disposed inside or outside the storage unit 50 and the storage unit 50. A nanobubble generator 52 that generates nanobubbles in the poor solvent L2 stored therein, and an ultrasonic generator 54 that is connected to the apparatus main body 12 and generates ultrasonic vibrations in the liquid in the flow path of the apparatus main body 12. , Configured to include a.

  The apparatus body 12 is formed by combining a substrate 26 and a cover plate 28, and a reaction groove, a solution introduction groove, and a poor solvent introduction groove are formed on the mating surface of the substrate 26. Then, the cover plate 28 is combined with the substrate 26 and integrated to form the reaction flow path 30, the solution introduction flow path 32, and the poor solvent introduction flow path 34, and the solution introduction flow path 32. And the poor solvent introduction channel 34 merge at the mixing unit 36 and are connected to the reaction channel 30. Thereby, the solution L1 and the poor solvent L2 merge at the mixing unit 36 of the reaction flow path 30 and are instantaneously mixed. The mixed solution L1 and poor solvent L2 are subjected to ultrasonic vibration by the ultrasonic generator 54 while passing through the reaction channel 30.

  Further, the two introduction flow paths 32 and 34 are respectively connected to the distal end portions of the respective pipes 14 and 16 through through holes 38 and 38 formed in the lid plate 28, and are connected to the base of the solution pipe 14. The solution supply means 18 is connected to the end, and the storage means 50 is connected to the base end of the poor solvent pipe 16. The storage unit 50 is connected to the poor solvent supply unit 20 and stores the poor solvent supplied from the poor solvent supply unit 20.

  The storage means 50 is provided with a nanobubble generator 52, which generates bubbles (hereinafter referred to as bubbles) in the poor solvent stored in the storage means 50. The diameter of the bubble to be generated is preferably 50 nm to 10 μm, more preferably 50 nm to 1 μm, and most preferably 50 nm to 100 nm. As the nanobubble generator, ENVIRANVISION YJ nozzle or the like can be preferably used. An ultrasonic generator can also be used as a nanobubble generator.

  For example, a microsyringe pump can be suitably used as a supply means for the solution L1 and the poor solvent L2. In this case, it is preferable that the solution supply means 18 and the poor solvent supply means 20 include an adjustment means (not shown) for adjusting the supply amount supplied to the apparatus main body 12.

  As the solution pipe 14 and the poor solvent pipe 16, a resin tube can be preferably used in addition to a metallic pipe. The outlet of the reaction channel 30 is connected to a discharge pipe (not shown) or the like through a through hole 40 formed in the lid plate 28.

  In FIG. 1, the solution L1 and the poor solvent L2 are respectively introduced into the mixing unit 36 by one introduction flow path 32, 34. As shown in FIG. More preferably, at least three or more are provided in total, and the solution introduction flow path 32 and the poor solvent introduction flow path 34 are alternately arranged.

  FIG. 2 is an explanatory view for explaining an example in which five introduction paths are provided in the fine particle production apparatus used in the present invention. As shown in FIG. 2, the apparatus main body 12 includes one reaction channel 30 and five introduction channels 32A, 32B, 32C, 34A, and 34B that radially diverge from the reaction channel 30. I have. As in the case of FIG. 1, the introduction channels 32A, 32B, and 32C are channels for introducing the solution L1, and the introduction channels 34A and 34B are channels for introducing the poor solvent L2. That is, an introduction channel 32A is provided on the opposite side of the reaction channel 30, and the introduction channels 34A and 34B are arranged in a V shape on the left and right sides of the introduction channel 32A. Further, the second and third introduction channels 32B and 32C are arranged in an inverted V shape on the left and right sides of the reaction channel 30.

  The reaction channel 30 communicates with the five introduction channels at the mixing section 36 corresponding to the inlet, and is introduced from the solution L1 introduced from the introduction channels 32A, 32B, and 32C and the introduction channels 34A and 34B. Organic pigment fine particles are produced by mixing with the poor solvent L2. The length of the reaction channel 30 is set to a length sufficient to produce organic pigment fine particles, for example, 0.5 mm to 100 mm. It is expected that particles can be formed even with a shorter flow path, but the above flow path length is appropriate in consideration of the processing accuracy of the reactor.

  In the above description, the case where a microreactor is used as a reaction device has been described as an example. However, the present invention is not limited to the reaction using a microreactor, and is generally used for other chemical reactions. Needless to say, the present invention can also be applied to the case of using a reaction apparatus, for example, the reaction using a tank stirring method.

  In the case of using a general chemical reaction apparatus including a tank agitation method, bubbles may be generated in the tank as a reaction field, or a poor solvent containing bubbles may be added to the tank (reaction field). good. In any case, any structure may be used as long as the fine particle crystal can be formed using the bubble as a nucleus.

<Fine particle production method>
Next, as an example of the fine particle production method of the present invention, a case where pigment fine particles are produced by a precipitation method will be described with reference to the drawings.

  The pigment to be prepared was PR254 (Ciba Specialty Chemicals). PR254 was dissolved in DMSO / alkali to prepare a pigment solution L1 having a concentration of 0.5 wt%. Ion exchange water was prepared as the poor solvent L2.

  A description will be given with reference to FIG. The solution L1 was charged from the solution supply means 18, and the poor solvent L2 was charged from the poor solvent supply means 20. The introduced poor solvent L2 is stored in the storage means 50, and the nanobubble generator 52 generates a large number of nanobubbles in the liquid of the poor solvent L2. The diameter of the nanobubbles to be generated is preferably 50 nm to 10 μm, more preferably 50 nm to 1 μm, and most preferably 50 nm to 100 nm. This is because if the bubble diameter is too large, the ascent rate will increase and problems such as blocking the flow path and generating a non-uniform field will occur. If it is too small, it will be sure that good results will always be obtained. This is because there is no (result). By generating nanobubbles in the range of 50 nm to 10 μm, the crystallinity becomes good and suitable for miniaturization.

  Here, an ultrasonic generator can also be used as the nanobubble generator. This generates bubbles in a vacuum cavity rather than just bubbles, and these bubbles can be used instead of bubbles. By using the bubbles in the vacuum cavity, there is an effect of enhancing the crushing effect. Moreover, you may generate | occur | produce in the poor solvent piping 16 instead of the storage means 50 as a place which generates a nano bubble in the poor solvent L2. In this case, a nanobubble generator is provided in the poor solvent pipe 16.

  The lysing solution L1 introduced from the lysing solution supplying means 18 is guided to the lysing solution introduction channel 32 of the apparatus main body 12 through the lysing solution pipe 14. The poor solvent L2 containing a large number of nanobubbles is guided from the storage means 50 through the poor solvent pipe 16 to the poor solvent introduction flow path 34 of the apparatus main body 12. The flow rate of the solution L1 flowing in the solution introduction flow path 32 is adjusted so that the pigment volume flow rate is 10 ml / min, and the flow rate of the poor solvent L2 flowing in the poor solvent introduction flow channel 34 is 100 ml / min. It is adjusted to become.

  As a method of adjusting the flow rate, adjustment by a valve or pressure can be adopted, but is not limited thereto.

  The solution L1 and the poor solvent L2 are mixed instantaneously in the mixing unit 36. At this time, since it was mixed with the poor solvent L2, the supersaturated pigment is precipitated. This precipitation is performed by agglomerating the pigment on the surface of the bubble contained in the poor solvent L2, and growing crystals of the aggregated pigment. The reason why the pigment aggregates on the surface of the bubble and the pigment crystal grows is considered to be the same principle that the crystal grows around the seed crystal that is usually used.

  When the pigment suddenly precipitates as a solid in the liquid, this change is unlikely to occur because energy corresponding to the enthalpy change accompanying the interface change for changing from the liquid-liquid interface to the solid-liquid interface is required. Therefore, when precipitation begins at a certain point, it becomes a large crystal quickly, so that it is difficult to form fine particles with good crystallinity, and it tends to be a crystal including an amorphous part.

  On the other hand, if a seed crystal is present, the seed crystal is a solid and has the same composition as itself, so that it is a change from a liquid-liquid interface to a solid-solid interface, and the amount of energy corresponding to the interface change can be reduced. Therefore, it slowly precipitates around the seed crystal and tends to grow. Therefore, fine particles with good crystallinity in which atoms are neatly arranged can be obtained.

  Here, when a bubble is used, since the bubble is a gas, the change is from the liquid-liquid interface to the solid-gas interface, and the change in interface energy is less than the change from the solid-liquid interface. Therefore, pigment crystals slowly precipitate and grow on the bubble surface, so that pigment fine particles with good crystallinity can be obtained. The present inventor has obtained the above idea through research and found that bubbles can replace seed crystals without using seed crystals. By using bubbles, a pigment having high crystallinity equivalent to that obtained by crystal growth using seed crystals could be obtained. In the case of the pigment PR254, the crystal form having the highest commercial value, such as a color filter, is the α type. However, without the bubble, the α crystallinity was about 60-75%. % Could be achieved. In addition, as the crystallinity increases, the particle size tends to increase, but the increase in size can be suppressed by the crushing effect of this method.

  The mixed liquid of the solution L1 and the poor solvent L2 instantaneously mixed in the mixing unit 36 precipitates a pigment on the surface of the bubble, and the precipitated pigment passes through the reaction flow path 30 while crystal growth occurs. At this time, ultrasonic vibration is applied to the liquid mixture by the ultrasonic generator 54. Thereby, the bubbles in the mixed solution passing through the reaction flow path 30 are pulverized by ultrasonic vibration, and the pigment particles on the bubble surface are in a dispersed state. Here, the conditions of the ultrasonic generator 54 are preferably a frequency of 20 kHz to 100 kHz and an output of 30 W to 3000 W, but more preferably an output condition of a frequency of 20 kHz and 500 W. The obtained pigment particles were applied to a Microtrac particle size distribution measuring device manufactured by Nikkiso Co., Ltd., and it was found that pigment particles having a particle size of 10 nm were obtained.

  The situation at this time will be described with reference to FIG. FIG. 3 is an explanatory diagram of the situation during bubble crushing. As shown in FIG. 3, many pigment particles 110 are condensed on the surface of the bubble 100 before being destroyed. The ultrasonic vibration is applied here, and the bubbles are destroyed, whereby the pigment particles 110 are in a dispersed state. Thereby, even if the adjacent pigment particles 110 form weak aggregates, they are finely dispersed by being crushed. That is, very fine particles can be obtained.

  Here, the bubble crushing means for crushing the bubbles is not limited to the ultrasonic generator, and a high shear stirrer can be used instead of the ultrasonic generator. In this case, the liquid mixture flowing out from the reaction flow path 30 in FIG. 1 is guided to a storage means in which a high shear stirrer is arranged, and the high shear stirrer is operated there, whereby bubbles can be destroyed.

  As another example, the crystal growth of the pigment particles can be continued on the bubble surface as it is without destroying the bubbles by applying ultrasonic vibration to the mixed solution. This will be described with reference to FIG. FIG. 4 is an explanatory diagram of hollow particle production.

  As shown in FIG. 4, when the condensation of the pigment particles on the surface of the bubble and the crystal growth of the pigment particles are continued, the surface of the bubble is covered with the pigment particles to form hollow particles. In this way, hollow particles can be formed. At this time, it is possible to produce hollow pigment particles having various functions by making the bubbles generated by the nanobubble generator 52 of FIG. 1 into various gas bubbles instead of air bubbles. For example, by using air bubbles containing a fragrance, pigment particles in which air containing a fragrance is contained in a hollow portion can be produced. Thereby, for example, when printing on paper with the ink containing this pigment particle with a printer etc., the fragrance | flavor of a fragrance | flavor can be drifted from a printed part by destroying a particle | grains by physically rubbing a printed part. Further, by using an inert gas bubble instead of an air bubble, for example, particles containing nitrogen gas in a hollow portion can be produced. Thereby, there exists an effect which suppresses oxidation from particle | grain inside.

  DESCRIPTION OF SYMBOLS 10: Fine particle manufacturing apparatus, 12: Apparatus main body, 14: Dissolution solution piping, 16: Poor solvent piping, 18: Dissolution solution supply means, 20: Poor solvent supply means, 26 Substrate, 28: Cover plate, 30: Reaction flow path 32: Solution introduction flow path, 32A: Introduction flow path, 32B: Introduction flow path, 34: Poor solvent introduction flow path, 34A: Introduction flow path, 36: Mixing section, 38: Through hole, 40: Through hole, 50: storage means, 52: nanobubble generator, 54: ultrasonic generator, 100: bubble, 110: pigment particles, L1: solution, L2: poor solvent

Claims (9)

A fine particle manufacturing method,
A bubble generating step for generating bubbles in a poor solvent having a low solubility of the fine particle forming material;
A mixing step in which a solution in which the fine particle forming material is dissolved and the poor solvent containing the bubbles are mixed, and
A method for producing fine particles, wherein the fine particles are deposited on the surface of the bubbles. The method further includes a step of pulverizing the bubbles after the mixing step.
The method for producing fine particles according to claim 1. The bubble has a diameter of 50 nm to 10 μm,
The method for producing fine particles according to claim 1 or 2. The bubbles are cavities generated by an ultrasonic generator;
The method for producing fine particles according to any one of claims 1 to 3.   2. The method for producing fine particles according to claim 1, further comprising the step of depositing the fine particles on the surface of the bubbles and then continuing the precipitation until the fine particles deposited on the entire surface of the bubbles are covered. A fine particle production apparatus for producing fine particles,
A solution supply means for supplying a solution in which the fine particle components are dissolved;
An anti-solvent supply means for supplying an anti-solvent having a small solubility of the fine particle components;
A bubble generator for generating bubbles in the poor solvent supplied from the poor solvent supply means;
A solution introduction flow path for circulating the solution supplied from the solution supply means;
A poor solvent introduction flow path for circulating a poor solvent in which bubbles are generated by the bubble generator;
A mixing unit for mixing the solution flowing out from the solution introducing flow path and the poor solvent flowing out from the poor solvent introducing flow path;
A reaction channel for circulating the mixed solution of the dissolving solution and the poor solvent mixed in the mixing unit;
Bubble crushing means for crushing bubbles in the mixed solution;
Fine particle manufacturing apparatus equipped with The bubble generator generates bubbles of 50 nm to 10 μm,
The fine particle manufacturing apparatus according to claim 6.   The microparticle production apparatus according to claim 6 or 7, wherein the bubble generator is an ultrasonic generator.   The fine particle production apparatus according to any one of claims 6 to 8, wherein the bubble crushing means is an ultrasonic generator.

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