JP2005205338A - Method for producing monodisperse particles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing monodisperse particles with high accuracy.
SOLUTION: In a first liquid as a continuous phase, a second liquid that becomes a dispersed phase and reacts with the first liquid and has a higher viscosity than the first liquid is passed through an orifice. In the method for producing monodisperse particles in the first liquid by discharging the liquid droplets, the second liquid is introduced into the orifice in a state in which the partition wall forming the orifice is immersed in the first liquid. To the first liquid.
[Selection] Figure 1

Description

  The present invention relates to a method for producing monodisperse particles with high accuracy.

  As a method for producing monodisperse particles, a wet method and a dry method are known as representative methods, but they are blended in pharmaceuticals, liquid crystal spacers, digital paper, display devices such as electrophoresis, paints and printing. In the field of matting agents, monodisperse particles are mainly produced by a wet method, since uniformity in particle size is required.

Conventionally, as a manufacturing method of monodisperse particles composed of microcapsules and simple materials by a wet method, “microcapsules—its functions and applications” (publishing agency: Japanese Standards Association, published March 20, 1991), “latest As introduced in “Microcapsulation Technology” (Issuing Center, Technical Center, Issued April 20, 1990), etc., interfacial deposition methods (for example, phase separation method, submerged drying method, melt dispersion method) Cooling method, suspension coating method) and interfacial reaction method (for example, interfacial polymerization method, in situ polymerization method, submerged curing coating method, interfacial reaction method), etc. It is known as a representative method.
However, since these conventional wet methods control the particle size of the monodisperse particles by adjusting the stirring conditions and the material concentration, it is difficult to control them, and variations have occurred even if not as dry methods. In the case of microcapsules, it is difficult to control not only the particle diameter but also the desired film thickness.

Therefore, as a method for solving the problems caused by these conventional wet methods, the liquid containing the remainder of the members constituting the microcapsule is included in the liquid to be discharged, which is a liquid containing a part of the members constituting the microcapsule. A method of producing microcapsules by ejecting from an orifice of an ink jet head positioned above a liquid to be ejected and reacting between the two liquids has been developed (for example, see Patent Document 1).
In this method, since the liquid ejected from the orifice becomes droplets of almost uniform size and is supplied into the liquid to be ejected, it is theoretically considered that uniform microcapsules are manufactured.
However, in this manufacturing method, the size of the liquid droplets is likely to change before the discharged liquid reaches the liquid to be discharged, and the discharged liquid has a deep portion of the liquid to be discharged due to the resistance of the liquid surface or the like. When it is difficult to get inside, it is easy to be distributed near the surface of the liquid to be ejected, and when the interval between the ejected liquid droplets is narrow, the liquid droplets coalesce before reaching the surface of the liquid to be ejected. As a result, there is a problem that uniform monodisperse particles are difficult to obtain.

JP 2001-232178 A

  Accordingly, the present invention has been made against the background of such problems of the prior art, and an object thereof is to provide a method for producing monodisperse particles with high accuracy.

As a result of intensive studies in order to achieve the above object, the present invention has found that the above object can be achieved by the following method, and has reached the present invention.
That is, the present invention provides a second liquid that is a dispersed phase in a first liquid as a continuous phase and that reacts with the first liquid and has a higher viscosity than the first liquid. In the method of producing monodisperse particles in the first liquid by discharging the liquid droplets through the first liquid, the second liquid is immersed in the first liquid with the partition wall forming the orifice immersed in the first liquid. The present invention relates to a method for producing monodisperse particles, characterized in that the droplets are discharged into the first liquid from an orifice.

  By the production method of the present invention, monodisperse particles can be produced with high accuracy.

Hereinafter, the present invention will be described in detail.
The present invention discharges a second liquid that is a particulate dispersed phase in a first liquid that is a continuous phase from an orifice such as an ink jet head described later, and a contact surface between the two liquids. In which the viscosity of the second liquid serving as the dispersed phase is higher than the viscosity of the first liquid serving as the continuous phase (feature 1).
Further, the second liquid serving as the dispersed phase is discharged in a state where the partition walls of the orifice are immersed in the first liquid serving as the continuous phase (feature 2).
Further, preferably, the contact angle of the second liquid with respect to the surface of the partition wall in contact with the continuous phase is larger than the contact angle of the first liquid with respect to the surface (feature 3).
When the second liquid is discharged into the first liquid, which is a continuous phase, pressure is applied to the second liquid for discharge. At this time, satellite particles are easily generated in addition to the target particles. According to the feature 1 of the present invention, by making the viscosity of the second liquid as the dispersed phase higher than the viscosity of the first liquid as the continuous phase, the discharge is smooth, the generation of satellite particles is suppressed, and the uniform monodisperse The effect of forming particles is obtained.

Further, according to the feature 2 of the present invention, the droplet of the second liquid that becomes a dispersed phase discharged as in the method of Patent Document 1 is not affected by the atmosphere before reaching the liquid to be discharged. There is little change in the size of the ejected droplets, resulting in uniform droplets, resulting in the effect of forming uniform monodisperse particles.
Furthermore, the feature 3 makes it easier for the discharged liquid droplets of the second liquid that becomes the dispersed phase to move deeper in the first liquid of the continuous phase, thereby preventing the liquid droplets from being coalesced. The effect of forming more uniform monodisperse particles can be obtained. In addition, when the contact angle of the liquid serving as the dispersed phase with respect to the partition wall is the same as or smaller than the contact angle of the first liquid serving as the continuous phase, the second liquid serving as the dispersed phase is used. The discharged droplets tend to be difficult to move to the deep part of the first liquid in the continuous phase, and some coalescence of the droplets due to distribution in the vicinity of the partition walls is seen, and as a result, uniform This tends to make it difficult to obtain monodisperse particles.

In the present invention, the contact angle is measured by a droplet method (for example, a contact angle meter CA-X type manufactured by Kyowa Interface Science Co., Ltd.).
In the present invention, the first liquid and the second liquid react when the two liquids come into contact with each other at the interface, and the surface of the second liquid (droplet) in the dispersed phase is the first liquid and the second liquid. A combination of various liquids can be used as long as it becomes a core-shell particle by solidification by an interfacial reaction.
Specifically, for example, a combination of an active hydrogen-containing compound such as polyamine or polyol and a compound such as acid chloride, polyisocyanate or epoxy resin, a combination of gelatin cation compound and arabic rubber anion compound, melamine and Various combinations introduced in combination with formalin or urea and other “latest microencapsulation technology” (Issue General Technology Center, issue date April 20, 1990) are possible.

In the present invention, as a combination of both liquids, a combination of compounds that are liquids, of course, even a solid compound, is used in a liquid state in combination with a solvent that dissolves or stably disperses the compound. It may be a combination of things. In addition, these liquids may be added to at least one side of both liquids, if necessary, a reaction accelerator for promoting the reaction, a retarding reaction retarding agent, a surfactant for adjusting the contact angle, a pigment, a dye, a conductive agent, an antiseptic. It is also possible to include an additive imparting various functions such as an agent. In the present invention, the reaction between the two liquids does not require the entire liquids to react with each other, but some components constituting each liquid react to form monodisperse particles. Also good.
In addition, when the concentration or viscosity of each component in the first liquid changes due to reaction with the second liquid or the like, in order to maintain the initial concentration or viscosity of each component of the first liquid, continuously or intermittently The first liquid replenisher may be replenished.
In the present invention, in order to produce uniform monodisperse particles, the viscosity of the liquid is important, and the viscosity of the second liquid needs to be higher than the viscosity of the first liquid.
That is, the viscosity of the first liquid and the second liquid is suitably about 20 mPa · s or less for the former, and the latter is higher than that, preferably 2 times or more, more preferably 4 to 10 times. A higher one is appropriate.

When the first liquid is higher than the viscosity range, the discharged second liquid tends to be difficult to enter the deep part of the first liquid. Moreover, when the viscosity of the second liquid is the same or lower than that of the first liquid, it is not preferable because satellite particles are easily generated and uniform monodisperse particles are hardly formed.
Next, the manufacturing method of the monodisperse particle of this invention is demonstrated based on FIG.
FIG. 1 shows a state in which an ink jet head 1 is immersed in a first liquid 2 that is a continuous phase, and a second liquid 3 is discharged as a droplet through an orifice 6 formed in a partition wall 4. FIG.

Although FIG. 1 shows an example in the case of one head, a system that uses a plurality of connected heads and forms a plurality of droplets at the same time may be used if necessary. Moreover, although FIG. 1 shows a case where the direction of the surface of the partition wall 4 is horizontal with respect to the direction of gravity, it is not necessarily horizontal.
The second liquid 3 that is a dispersed phase introduced into the head 1 is ejected from the orifice 6 into the first liquid that is the continuous phase by a change in pressure at a constant pressure or a constant interval, and is a droplet that has become a dispersed phase. 5 is formed. As a method for applying pressure to the second liquid to be a dispersed phase, for example, a method using a water level difference, a method of pushing at a constant speed by a syringe, a pump, or the like can be given as representative methods. Moreover, as a method of changing the pressure of a fixed space | interval, the method of vibrating a syringe piston, the method using a piezoelectric element, etc. are mentioned as a typical method, for example.

The diameter of the orifice 6 is usually 0.1 to 500 μm, preferably 10 to 100 μm. If it is less than 0.1 μm, nozzle clogging tends to occur, while if it exceeds 500 μm, it is uniform. Discharge control becomes difficult, and it tends to be difficult to form uniform droplets.
Further, the discharge speed is not particularly limited, but 1 to 5000 drops / second, preferably 10 to 1000 drops / second is appropriate.
In the present invention, the particle size of the monodisperse particles is mainly adjusted by the diameter of the orifice 6, but in the method using a piezo element, it can also be adjusted by changing the applied voltage.
In the present invention, the orifice 6 is not particularly limited as long as it can discharge liquid. The orifice 6 preferably used is an orifice of an ink jet head.

  As described above, the surface of the partition wall 4 prevents the droplets 5 discharged from the second liquid serving as the dispersed phase from moving easily to the deep portion in the first liquid 2 in the continuous phase and preventing the droplets 5 from being distributed in the vicinity of the partition wall. Therefore, the contact angle of the second liquid serving as the dispersed phase with respect to the surface of the partition that is in contact with the continuous phase, that is, the surface where the orifice is formed, is the contact angle of the first liquid that is the continuous phase with respect to the surface. It is preferable to make it larger than the corner. Therefore, the partition should just be formed with the process or the raw material so that the surface may have the above characteristics. However, it is necessary to select the material of the surface on the side in contact with the continuous phase of the partition that does not change due to chemical reaction or the like with both liquids.

Suitable examples of the material on the surface of the partition that is in contact with the continuous phase include inorganic materials such as ceramic, glass, and various metals, and organic materials such as various plastics.
If the material of the surface of the partition that is in contact with the continuous phase itself satisfies the contact angle condition, it can be used without treatment, but the second liquid that becomes the dispersed phase and the first phase of the continuous phase can be used. When the contact angle condition is not satisfied depending on the type of one liquid, the contact angle condition may be satisfied by surface-treating the surface of the partition that is in contact with the continuous phase.
As a method of surface treatment, for example, a method of applying various resins, a method of depositing a metal or an oxide thereof, a method of attaching a film made of a resin or a metal, Typical examples include laser beam / ultraviolet light irradiation treatment, plasma discharge treatment, acid treatment and the like, but the method is not limited to these methods.

In general, if the relationship between the second liquid that is the dispersed phase and the first liquid that is the continuous phase is W / O (oil-in-water), the material on the surface of the partition that is in contact with the continuous phase is It is appropriate to make the resin lipophilic with a silicone resin, a fluororesin or the like. On the other hand, if it is O / W, the surface of the material is subjected to laser light / ultraviolet light irradiation treatment, plasma discharge treatment, acid treatment, vapor deposition treatment of titanium oxide, silica, alumina, etc., or coating of hydrophilic resin such as polyvinyl alcohol. Therefore, it is appropriate to make it hydrophilic.
It is desirable that the surface of the partition that is in contact with the continuous phase satisfies the contact angle condition for the entire surface, but in some cases, only the surface around the orifice satisfies the contact angle condition. There may be.
As described above, the contact angle of the second liquid serving as the dispersed phase with respect to the surface of the partition wall in contact with the continuous phase is larger than the contact angle of the first liquid serving as the continuous phase with respect to the partition wall. However, it is particularly preferable that the contact angle θ of the second liquid serving as the dispersed phase with respect to the partition wall is 10 ° <θ <180 °, and the contact angle θ of the first liquid serving as the continuous phase with respect to the partition wall is 0. Desirably, ° <θ <150 °, and the former contact angle is 10 ° or more, particularly preferably 70 ° or more larger than the latter contact angle.

In the first liquid that is the continuous phase, the present invention disperses the second liquid that becomes the dispersed phase in the form of droplets, and the head is immersed in the first liquid that is the continuous phase, or After taking out from the first liquid, the reaction is completed by allowing it to stand naturally or, if necessary, by heating or the like to produce monodisperse particles. The monodisperse particles produced in this way are commercialized as they are or as they are taken out from a liquid that is a continuous phase and dried.
Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, these examples and comparative examples do not limit the scope of the present invention.

Examples 1 to 3 and Comparative Example 1 (W / O type)
A 20 ° C. second liquid (a mixture of water, polyvinyl alcohol (degree of polymerization: 500) and diethylenetriamine in a proportion shown in Table 1) serving as a dispersed phase was applied to a piezo-type inkjet discharge device [HEK-1 (manufactured by Konica Corporation). ), With an orifice diameter of 40 μm], the partition wall of the material shown in Table 1 of the apparatus is a continuous liquid of 20 ° C. first liquid [toluene and epoxy resin [Epicoat 828 (manufactured by Japan Epoxy Resin Co., Ltd.)]. It was discharged at a discharge speed of 100 drops / second in a state of being immersed in a mixture of hexaglycerin condensed ricinoleate (manufactured by Sunsoft Co., Ltd.). The discharge conditions of HEK-1 are D time (Draw Time) 12 μsec (voltage 12 V), RR time (Release and Reinforce Time) 24 μsec (voltage 12 V). After completion of the discharge, the mixture was heated to 50 ° C. and held for 4 hours.
The image of the obtained dispersion liquid was photographed with a CCD camera (DXC-990MD: manufactured by SONY Corporation) through a microscope (BX51: manufactured by OLYMPUS Corporation), captured in a computer, and WinRoof (manufactured by Mitani Corporation). ) Was used for calibration with a reference scale (OB-M 1/100: manufactured by OLYMPUS Co., Ltd.), and the particle size distribution of each monodisperse particle was measured (the number of particles measured was 200 or more). The results are shown in the lower part of Table 1.

Note 1), Note 2) Contact angle with the surface of the partition that is in contact with the continuous phase Note 3) Coefficient of variation of particle size distribution CV (CV value is smaller as particle size is uniform)
(Evaluation) ◎: CV = 10% or less, ○: CV = 11-20%
Δ: CV = 21-30%, X: CV = 30% exceeded, or particles could not be formed

Examples 4 to 5 and Comparative Example 2 (O / W type)
A second liquid [a mixture of the composition shown in Table 2 consisting of dodecane, hexamethylene diisocyanate and hexamethylene diisocyanate isocyanurate type [Takenate D177N (manufactured by Mitsui Takeda Chemical)]] serving as a dispersed phase was added to the piezo. A first liquid [water and polyvinyl chloride] of 10 ° C., which is a continuous phase, is formed by separating the partition walls of the material shown in Table 2 of the apparatus with a type inkjet discharge device [HEK-1 (manufactured by Konica Corporation), orifice diameter 40 μm]. It was discharged at a discharge speed of 100 drops / second in a state immersed in an alcohol (polymerization degree 500) and a mixture of the composition shown in Table 2 consisting of diethylenetriamine. The discharge conditions of HEK-1 are D time 12 μsec (voltage 12 V), RR time 24 μsec (voltage 12 V). After completion of the discharge, the mixture was heated to 80 ° C. and held for 6 hours.
For the obtained dispersion, the particle size distribution of monodisperse particles was measured in the same manner as in Example 1, and the results are shown in the lower part of Table 2.

  As is clear from the results in Tables 1 and 2, uniform monodisperse particles were obtained in Examples 1 to 5, which are the production methods of the present invention. On the other hand, in Comparative Examples 1 and 2 using the second liquid having a lower viscosity than the first liquid as the continuous phase, all became non-uniform particles.

The figure which shows the state from which the 2nd liquid used as a dispersed phase is discharged in the 1st liquid which is a continuous phase from the orifice of this invention, and the droplet of a 2nd liquid moves to a deep part.

Claims (4)

  In a first liquid as a continuous phase, a second liquid that is a disperse phase and reacts with the first liquid and has a higher viscosity than the first liquid is dropped through an orifice. In the method for producing monodisperse particles in the first liquid, the second liquid is discharged from the orifice in the state in which the partition wall forming the orifice is immersed in the first liquid. A method for producing monodisperse particles, characterized by being ejected as droplets.   2. The method for producing monodispersed particles according to claim 1, wherein a contact angle of the second liquid with respect to a surface of the partition wall in contact with the continuous phase is larger than a contact angle of the first liquid with respect to the surface.   The contact angle θ of the second liquid with respect to the surface of the partition that is in contact with the continuous phase is 10 ° <θ <180 °, and the contact angle θ of the first liquid with respect to the surface is 0 ° <θ. The method for producing monodispersed particles according to claim 2, wherein <150 ° and the contact angle θ of the second liquid is 10 ° or more larger than the contact angle θ of the first liquid.   The method for producing monodisperse particles according to any one of claims 1 to 3, wherein the orifice has a diameter of 0.1 to 500 µm.

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