JP4537421B2 - Method for producing monodisperse particles - Google Patents

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 the uniformity of 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 member constituting the microcapsule is contained in the liquid to be discharged, which is a liquid containing a part of the member constituting the microcapsule. A method of producing microcapsules by ejecting from an orifice of an ink jet head located above a liquid to be ejected and reacting between the two liquids has been developed (for example, see Patent Document 1).

JP 2001-232178 A

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.

  Therefore, 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, according to the present invention, a second liquid that becomes a dispersed phase and reacts with the first liquid is discharged as droplets through an orifice into the first liquid as a continuous phase. In the method for producing dispersed particles, the second liquid is O / W (oil-in-water) with respect to the first liquid, and the orifice plate is subjected to a hydrophilic surface treatment to form the orifice. The second liquid in a state where the contact angle of the second liquid with respect to the orifice plate surface is larger than the contact angle of the first liquid with respect to the orifice plate surface and the orifice plate surface is immersed in the first liquid. Is discharged from the orifice into the first liquid.

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 the method of producing monodisperse particles in a solid state, when the second liquid serving as the dispersed phase is discharged, the orifice plate surface of the orifice is immersed in the first liquid serving as the continuous phase. It is a feature (feature 1) that the ink is discharged in a discharged state.
The orifice plate surface is characterized in that the contact angle of the second liquid serving as the dispersed phase with respect to the plate surface is larger than the contact angle of the first liquid serving as the continuous phase with respect to the plate surface (feature 2). Yes.

According to the feature 1 of the present invention, the liquid droplets of the second liquid, which is the dispersed phase discharged as in the method of Patent Document 1, are not affected by the atmosphere until reaching the liquid to be discharged, and thus discharged. There is little change in the size of the droplets, resulting in uniform droplets. As a result, the effect of forming uniform monodisperse particles can be obtained.
In addition, the feature 2 makes it easier for the discharged liquid droplets of the second liquid serving as the dispersed phase to move deeper in the first liquid of the continuous phase, so that the liquid droplets do not coalesce. The effect of forming uniform monodisperse particles can be obtained. In addition, when the contact angle of the liquid serving as the dispersed phase with respect to the orifice plate surface 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 ejected droplets are difficult to move to the deep part of the first liquid in the continuous phase, and are easily distributed near the orifice plate surface, so that the droplets are likely to coalesce, resulting in uniform monodisperse particles. Since it becomes difficult, it is not preferable.

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 that is a continuous phase and the second liquid (droplet) that has become a dispersed phase in the first liquid that is the continuous phase react by contacting both liquids at the interface, A combination of various liquids can be used as long as the surface of the second liquid (droplet) in the dispersed phase becomes solidified particles.
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 formalin Alternatively, combinations with urea, and other combinations introduced in “Latest Microcapsulation Technology” (Issuing Center, Technical 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, in combination with a solvent that dissolves or stably disperses the compound, A combination of these may be used. In addition, these liquids have various functions such as a curing accelerator that promotes the reaction, a surfactant that adjusts the contact angle, a pigment, a dye, a conductive agent, an antiseptic, etc. on at least one side of both liquids as necessary. It is also possible to include an additive for imparting. Further, in the present invention, the reaction between the two liquids does not require the entire liquids to react with each other, and some components constituting each liquid react to form monodisperse particles. Also good.
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 that is a dispersed phase is discharged through an orifice 6 formed by an orifice plate 4. FIG. 5 is a schematic explanatory view for forming a droplet 5

Although FIG. 1 shows an example in the case of one head, a system in which a plurality of connected heads are used and a plurality of droplets are simultaneously formed may be used as necessary. . Further, FIG. 1 shows a case where the orientation of the surface of the orifice plate 4 is horizontal with respect to the direction of gravity, but it is not necessarily horizontal.
The second liquid 5, which is a dispersed phase introduced into the head 1, is discharged from the orifice 6 into the first liquid, which is the continuous phase, by a change in pressure at a constant pressure or at constant intervals.
In addition, as a method of applying a constant pressure to the second liquid to be a dispersed phase, for example, a method using a difference in water level, 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 500 to 3000 drops / second is appropriate.
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 orifice plate 4 is easily distributed to the deep part of the first liquid 2 in the continuous phase and the liquid droplets 5 discharged from the second liquid serving as the dispersed phase are distributed in the vicinity of the orifice plate surface. The surface properties are important to prevent That is, the contact angle of the second liquid serving as the dispersed phase with respect to the orifice plate surface may be larger than the contact angle of the first liquid serving as the continuous phase with respect to the orifice plate surface. Therefore, the orifice plate should just be formed by the process or the raw material so that the surface may have the above characteristics at least. However, it is necessary to select the material of the plate surface that does not change due to chemical reaction or the like with both liquids.

Suitable examples of the material for the orifice plate surface include inorganic materials such as ceramics, glass and various metals, and organic materials such as various plastics.
If the material of the orifice plate surface itself satisfies the contact angle condition, it can be used without treatment, but depending on the type of the second liquid serving as the dispersed phase and the first liquid serving as the continuous phase, When the contact angle condition is not satisfied, the contact angle condition may be satisfied by surface-treating the material surface of the orifice plate surface.
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 a method of modification by laser light / ultraviolet light irradiation treatment, plasma discharge treatment, acid treatment, and the like, but are 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 (water-in-oil), the material of the orifice plate surface is silicone resin, fluororesin, etc. It is appropriate to make it lipophilic. 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 or the like, or application of hydrophilic resin such as polyvinyl alcohol. Therefore, it is appropriate to make it hydrophilic.

The orifice plate surface is a surface in contact with the first liquid which is a continuous phase on the side where the orifice for discharging droplets is present. The surface should satisfy the contact angle condition for the entire surface. However, in some cases, only the orifice plate surface around the orifice may satisfy the contact angle condition.
As described above, the contact angle of the second liquid serving as the dispersed phase with respect to the orifice plate surface needs to be larger than the contact angle of the first liquid serving as the continuous phase with respect to the orifice plate surface. Preferably, the contact angle θ of the second liquid that is a dispersed phase with respect to the orifice plate surface is 10 ° <θ <180 °, and the contact angle θ of the first liquid that is a continuous phase with respect to the orifice plate surface is 0 °. <Θ <150 °, and the former contact angle is 10 ° or more, particularly preferably 70 ° or more larger than the latter contact angle.

The present invention thus disperses the second liquid, which is the dispersed phase, in the state of droplets in the first liquid, which is the continuous phase, and after the head is taken out from the first liquid, which is the continuous phase, The reaction is completed by leaving or, if necessary, heating 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.

Examples 1-2 and Comparative Examples 1-2
2 parts by mass of second liquid [88 parts by mass of dodecane, 10 parts by mass of hexamethylene diisocyanate, isocyanurate type of hexamethylene diisocyanate [Takenate D177N (manufactured by Mitsui Takeda Chemical Co., Ltd.)] as a dispersed phase at 10 ° C. The mixture] is an inkjet discharge device [HEK-1 (manufactured by Konica Co., Ltd.), orifice diameter 20 μm], and the orifice plate surface of the material shown in Table 1 of the device is the first liquid at 10 ° C. which is a continuous phase. It was discharged at a discharge speed of 800 drops / second in a state of being immersed in [mixture of 495 parts by weight of water and 5 parts by weight of polyvinyl alcohol].
After completion of the discharge, the mixture was heated to 80 ° C. and held for 6 hours.
With respect to the obtained dispersion, the particle size distribution of monodisperse particles was measured, and the results are shown in the lower part of Table 1.
In addition, Examples 1-2 and Comparative Examples 1-2 are a thing of an O / W state.

Note 1) The surface is covered with fluororesin paint [V Freon (Dainippon Paint Co., Ltd.)].
Note 2) A: Contact angle of the second liquid that is the dispersed phase with respect to the orifice plate material B: Contact angle of the first liquid that is the continuous phase with respect to the orifice plate material Note 3) Coefficient of variation CV (small CV value) of the particle size distribution The particle size is so uniform)
Evaluation: ◎: CV = 10% or less, ○: CV = 11-20%, Δ: CV = 21-30%
×: CV exceeds 30% or particles cannot be formed

  As is clear from the results in Table 1, uniform monodisperse particles were obtained in Examples 1 and 2 as the production method of the present invention. On the other hand, in Comparative Examples 1 and 2 in which the contact angle of the second liquid body serving as the dispersed phase with respect to the orifice plate surface is smaller than the contact angle of the first liquid serving as the continuous phase with respect to the orifice plate surface, both become non-uniform particles. It was.

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

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 (5)

A method of producing monodisperse particles in a first liquid as a continuous phase by ejecting a second liquid that becomes a dispersed phase and reacts with the first liquid as droplets through an orifice. The second liquid forms droplets in the first liquid as O / W (oil-in-water) with respect to the first liquid, and the orifice on the side in contact with the first liquid the orifice plate surface to form Yes surface treated hydrophilic, the contact angle of the second liquid to the orifice plate surface is greater than the contact angle of the first liquid to the orifice plate surface, and the orifice plate surface wherein in a state of being immersed in the first liquid, the second liquid is discharged into the first liquid from said orifice, and both solutions react at the interface between the first liquid and the second liquid, the surface And forming a solidified particles, method for producing monodisperse particles.   The contact angle θ of the second liquid with respect to the orifice plate surface is 10 ° <θ <180 °, and the contact angle θ of the first liquid with respect to the orifice plate surface is 0 ° <θ <150 °, The method for producing monodisperse particles according to claim 1, wherein 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 claim 1 or 2, wherein the orifice has a diameter of 10 to 100 µm.   The method for producing monodisperse particles according to claim 1, wherein the orifice is an ink jet head.   The method for producing monodisperse particles according to any one of claims 1 to 4, wherein the orifice plate is surface-treated by plasma discharge treatment.

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