JP2854390B2 - Method for forming uniform droplets - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for forming droplets having a uniform and fine diameter.

[Prior art] Uniform and fine droplets of a solution of a polymer substance or a vinyl polymerizable monomer solution are formed into fine droplets, and particles having a uniform and fine diameter obtained by gelling or polymerizing the droplets are functionally adsorbed. They are extremely useful as agents and carriers.

Conventionally, as a method for forming such uniform and fine droplets, a method of mechanically applying vibration at a fixed period (hereinafter referred to as a mechanical method) or a method of applying an AC voltage (hereinafter, referred to as a
Electric type) is known.

In the mechanical type, when a fluid is ejected from a nozzle as a liquid column into a gas or a dispersion medium, a constant period of mechanical vibration is applied to form uniform droplets synchronized with the frequency ( JP-A-57-102095, JP-A-61-83202
No.). However, in this method, the frequency must be increased in order to make the droplet smaller, but in order to obtain a synchronized state with this higher frequency, the nozzle diameter must be reduced and the ejection speed must be increased. . However, in the method of ejecting the liquid into the dispersion medium, if the ejection velocity is increased, the liquid column is destroyed by friction with the dispersion medium.
The method of injecting into a gas has a problem that the droplets coalesce because they float in the gas for a long time, and the former can form only a droplet of at most 500 μm, and the latter can form only a droplet of up to 200 μm.

The electric method forms a number of droplets in the dispersion medium synchronized with the AC cycle by ejecting the liquid from the nozzle while applying a high-frequency AC voltage with a fixed cycle between the nozzle and the electrode installed in the dispersion medium. According to this electric method, an electric field that changes at a constant period is applied between a nozzle and an electrode, and the liquid ejected from the nozzle into the dispersion medium is changed by the change in the electric field. Since the column is cut, a suspension of fine droplets can be obtained directly, there is no environmental problem due to mechanical vibration, and the frequency can be easily maintained stably.

[Problems to be Solved by the Invention] As described above, the electric type is a method superior to the mechanical type in many points, but in order to obtain a synchronous state necessary for cutting the liquid column, the liquid ejection hole of the nozzle is required. Except that it needs to be electrically insulated and requires high voltage. For this reason, the insulating coating of the nozzle is broken or the nozzle or the electrode is corroded, and it is difficult to continuously and stably produce uniform droplets. In addition, although the electrical type is not as good as the mechanical type, since the generated fine droplets remain in the droplet generation area, the prevention of coalescence of the droplets is insufficient. Furthermore, since droplets are generated by reflecting the change in the electric field on the dispersion medium, there are severe restrictions on the electrical properties of the usable dispersion medium.

The present invention relates to a method for solving the problems of the method of forming such an electric uniform fine droplet, which is excellent in the effect of preventing coalescence at a low voltage, and in which uniform liquid droplets in which restrictions on a dispersion medium to be used are eased. The present invention provides a forming method.

[Means for Solving the Problems] In the method for forming a uniform droplet according to the present invention, a liquid ejection nozzle, an electric insulating plate provided with a passage hole for the liquid, and an electrode are arranged in this order in a dispersion medium. In this method, a liquid is ejected from a nozzle while applying a voltage of a certain period between the nozzle and the electrode, thereby generating a uniform number of droplets in synchronization with the period of the voltage.

[Operation] The method of the present invention will be described with reference to FIGS. First
FIG. 1 is a schematic longitudinal sectional view of one embodiment of a dispersion apparatus that can be employed when carrying out the method of the present invention, and FIG. 2 is a schematic view for explaining an electric field formed in the embodiment shown in FIG. It is sectional drawing.

In the embodiment of the droplet forming dispersion apparatus shown in FIG. 1, the outer wall portion is made of an electrical insulator, for example, polytetrafluoroethylene, acrylic resin or the like.
The liquid used as the droplet (1) is ejected from the ejection hole (3) of the conductive nozzle (2) into the dispersion medium (4). Nozzle (2)
An electric insulating plate (5) is disposed in front of the nozzle so as to be parallel to the nozzle, and a hole (6) of the insulating plate (5) is provided at a position coaxial with the nozzle hole (3). I have. Further, behind the insulating plate (5), an electrode (11) is arranged in parallel with the insulating plate (5), and a through hole (13) for a droplet or the like is provided in a central portion thereof. An AC voltage is applied between the nozzle (2) and the electrode (11) from a power supply (14).

According to the method of the present invention, uniform fine droplets can be formed at a low voltage while preventing coalescence of droplets.

That is, the insulating plate (5) provided with the hole (6) is connected to the electrode (1).
By placing it between 1) and nozzle (2), the second
As shown by the lines of electric force in the figure, the electric field between the nozzle and the electrode converges at the hole (6) of the insulating plate (5), and the electric field density at that portion is greatly increased. As a result, the voltage actually applied between the nozzle and the electrode is amplified near the hole (6),
Even at a low voltage, the same effect as when a high voltage is applied in the conventional method can be obtained. This is also evident from the fact that the production of droplets in the method of the present invention occurs near the hole (6). By this electric field convergence action, the applied voltage can be reduced to several hundredth of the conventional voltage, and as a result, the corrosion of the nozzle and the electrode can be suppressed.

In addition, the passage of the liquid and the dispersion medium is only the hole (6) of the insulating plate (5) (flow contraction action), and the droplet (1) generated near the hole (6) is immediately retained without staying in the vicinity. Riding in the flow, it can be avoided from the hole (6). Therefore,
The probability that the generated droplets collide and coalesce is greatly reduced (coalescence preventing effect).

Furthermore, in the conventional method, a dispersion medium having a large electric conductivity cannot be used. However, since the dispersion medium is partitioned by the insulating plate (5), the dispersion medium after the insulating plate, that is, does not contribute to the generation of droplets. There is no need to limit the dispersion medium due to its electrical properties, and it is possible to use a dispersion medium that is effective for preventing coalescence.

The basic aspects and operational effects of the method of the present invention have been described above. Other aspects and operational effects will be clarified in the following examples.

Example The liquid for forming droplets suitably used in the present invention is a solution of a polymer substance or a liquid containing a vinyl polymerizable monomer. After dispersing these liquids into uniform droplets according to the method of the present invention, when the liquid is a solution of a polymer substance, the solvent in the droplets is volatilized by heating or gelled by cooling. Alternatively, the droplets are coagulated by adding a gelling accelerator to the dispersion, and when the liquid is a liquid containing a vinyl polymerizable monomer, the liquid is polymerized to form a uniform dispersion from these droplets. Particles having a particle diameter are obtained. These particles are useful as excellent functional adsorbents and carriers.

First, the case where a solution of a polymer substance is used will be described in more detail.

As the polymer substance, any substance which is generally soluble in a solvent can be used, and a substance suitable for the purpose of use may be selected. The polymer may be a natural polymer,
It may be a synthetic polymer.

Examples of natural polymeric substances include, for example, cellulose,
Natural polymer substances such as agarose, carrageenan, alginate, silk fibroin, collagen, chitin and derivatives thereof are mentioned. Examples of the synthetic polymer include polyvinyl alcohol, poly-γ-methyl-L-glutamate, and methyl methacrylate / hydroxyethyl methacrylate copolymer. A polymer capable of introducing a crosslink and an ion exchange group, such as a styrene / butadiene copolymer and a styrene / chloromethylated styrene copolymer, is also useful as a base material of the ion exchange resin.

These polymer substances are used in the present invention after being dissolved in a hydrophobic or hydrophilic solvent. As the solvent, a liquid that is incompatible or poorly compatible with a dispersion medium described below is selected.

Solvents for natural polymer substances and their derivatives are described in “Natural Polymers” (1984)
Published by Kyoritsu Shuppan Co., Ltd. or SAMUEL M.HUDSON and JO
HN A. CUCULO, Journal of macromolecular Science-Rev
iews in Macro-molecular Chemistry and Physics, C1
8 (1), pp. 1-82, 1980, and the like. In addition, solvents for synthetic polymer substances are J. Brandrup, Po.
lymer Handbook, 2nd, edition, John Wiley and Sons
Inc., 1975, etc.

As the hydrophobic solvent, for example, chlorinated hydrocarbons such as methylene chloride, chloroform, dichloroethane and the like are usually used alone or as a mixture of two or more kinds. A small amount of a lower alcohol such as methanol or ethanol can be added to these solvents as a coagulation accelerator. Further, an aliphatic alcohol having 4 to 12 carbon atoms can be added to make the polymer particles porous. As the hydrophilic solvent, water-soluble solvents such as water, acetone, tetrahydrofuran, dioxane, dimethylformamide, dimethylacetamide, dimethylsulfoxide, and N-methyl-2-pyrrolidone are usually used. Water-soluble lower alcohols, water-soluble polyhydric alcohols, inorganic salts, and the like can be added to these to promote coagulation or make the polymer particles porous.

The viscosity of the solution of the polymer substance is 50 cps or less, preferably 2 cps.
It is less than 0cps. If the viscosity is greater than 50 cps, it is difficult to form droplets synchronized with the AC voltage. Further, the electric conductivity of this solution is not particularly limited.

In the present invention, droplets are formed by ejecting a solution of the above-mentioned polymer substance from a nozzle into a dispersion medium incompatible or poorly compatible with the solvent.

As the dispersion medium, when the solvent of the polymer substance is hydrophobic, a nonionic surfactant such as gelatin, methylcellulose, polyvinyl alcohol, polyoxyethylene sorbitan monohydrate is formed so that an O / W type dispersion medium can be formed. An aqueous solution to which 0.2 to 5% (wt%, the same applies hereinafter) of lauryl ether, polyethylene glycol monostearate or the like is added is usually used. Conversely, when the solvent of the polymer substance is hydrophilic, a hydrophobic organic liquid is used as the dispersion medium. For example, hydrocarbon-based liquids such as liquid paraffin, ligroin, and tetralin, vegetable oils such as rapeseed oil and cottonseed oil, and halogenated hydrocarbon-based solvents such as carbon tetrachloride and 1,1,2,2-tetrachloroethane are used. These are made of HLB (Hydrophilic-lip) so as to form a W / O type dispersion.
ophilic-Balance) (Hiroguchi Hiroshi, “New surfactant”, 63
Pp. 70, published by Sankyo Shuppan Co., Ltd., 1981), and 3 to 7 surfactants such as glycerol monostearate, glycerol monooleate, and sorbitan monooleate are added in an amount of 0.5 to 5%.

The viscosity of the dispersion medium is preferably 50 cps or less, more preferably 20 cps, and particularly preferably 5 cps or less. When the viscosity is increased, when the liquid is ejected from the nozzle at a high flow rate, the jet flow is broken by the viscous resistance, and it tends to be difficult to form a uniform droplet.

The electric conductivity of the dispersion medium is 10 ^{-10 to} 100 μs / cm,
^It is preferably ^{-7 to} 10 μs / cm. Also, if the difference between the dielectric constants of the droplet forming liquid and the dispersion medium is too large or too small, it tends to be difficult to form uniform droplets. The reason for this has not been fully elucidated, but it is presumed that if the electric conductivity is too large, it is difficult to generate an electric tension in the converging portion of the electric field near the hole of the insulating plate. In addition, when the electric conductivity is small and the dielectric constant is small, it is considered that the degree of convergence of the electric field near the hole of the insulating plate becomes small.

The voltage for achieving the synchronization state is between several volts and several hundred volts when the electric conductivity of the dispersion medium is relatively large, but is about 100 volts to several thousand volts when the electric conductivity of the dispersion medium is small. Between bolts. According to the conventional electric system, the former requires several hundred volts or more, and the latter requires several thousands volts or more.

In the present invention, since the ejection of the liquid is performed in the dispersion medium, the droplets are combined with the droplets ejected later to increase the particle size, as in the method of forming droplets in a gas, Almost no adhesion to the electrode occurs. In addition, since droplets are formed by periodic changes in voltage and do not rely on mechanical vibration, the particle size can be reduced without increasing the ejection speed so much, there is no noise problem, and the cycle is stable. Therefore, the particle diameter of the droplet is stabilized.

Next, the droplet forming method of the present invention will be specifically described with reference to FIGS. FIG. 3 is a schematic sectional view showing the state of an electric field of another dispersing device usable in the method of the present invention. In addition, in FIGS. Indicates that the part is a conductive material, Indicates that it is an insulating material. The curves in FIGS. 2 and 3 show the state where the lines of electric force converge at the hole (6) of the insulating plate (5).

As shown in FIG. 1, a solution of a polymer substance is fed into a droplet forming dispersing device at a constant flow rate as shown by an arrow.
It is jetted from the jet hole (3) of the nozzle (2) toward the hole (6) of the insulating plate (5). In the embodiment shown in FIG. 1, the nozzle (2) is conductive, such as metal,
As shown in FIG. 3, the periphery of the nozzle hole (3) may be made insulative and the other parts may be made conductive. These nozzles are not provided with any insulating coating as in the conventional method. In the apparatus illustrated in the drawings, a single-hole nozzle is used, but a multi-hole nozzle can of course be used. The diameter of the nozzle hole (3) is usually 20 to 250 μm, but it is preferable that the diameter is 200 μm or less in order to form a droplet having a relatively small particle diameter of 250 μm or less, so as to avoid clogging of the nozzle. For this purpose, the thickness is preferably 30 μm or more. The diameter of the hole (6) of the insulating plate (5) is preferably 2 to 100 times the diameter of the nozzle. The reason why the holes are provided in the insulating plate is to concentrate the electric field, and it is not preferable that the number exceeds 100 times. However, if it is too small, unnecessarily high assembling accuracy is required or a large pressure is applied to the insulating plate. The distance between the nozzle (2) and the insulating plate (5) is preferably 50 μm to 10 mm. If this interval is less than 50 μm, the electric field may concentrate on the nozzle portion near the hole (6) of the insulating plate, as in the conventional method, and corrosion may occur. In addition, there is a possibility that the flow of the dispersion medium accompanied by the liquid ejected from the nozzle becomes uneven. However, if this interval exceeds 10 mm, the electric field is not concentrated at the position where the droplet is formed, and a uniform droplet cannot be formed.

The first dispersion medium (4a) is sent from the inlet (7) to the space (8) between the nozzle (2) and the insulating plate as shown by the arrow. The dispersion medium (4a) is ejected from the hole (6) of the insulating plate while entraining the liquid coming out of the hole (3) of the nozzle. At this time, it is also possible to reduce the accompanying liquid by adjusting the flow rate of the dispersion medium and use the same nozzle to form smaller droplets.
In the present invention, a dispersion medium (4b) different from the initial dispersion medium (4a) can be supplied to the dispersion tank (10) from the inlet (9). For example, a surfactant can be added to the dispersion medium (4b) to stably maintain the dispersion of the droplets and to provide an effect of preventing coalescence of the generated droplets.

The electrode (11) may be made of metal such as stainless steel as shown in FIG. 1 and may be installed at a distance of about 10 to 50 mm from the nozzle, or as shown in FIG. The outer wall after the plate (5) may be made of a conductive material and used as the electrode (12). Electrode in Fig. 1 (11)
Has a diameter of 10 through which droplets formed in the dispersion tank (10) pass.
A hole (13) of about 20 mm is open. The electrode (11) is connected to the nozzle (2) via a power supply (14) for applying a voltage that changes at a constant cycle. In general, a treatment (not shown) for converting the droplets into polymer particles is applied to the dispersion of the uniform droplets that have passed through the electrodes.

The discharge amount of the droplet from the nozzle is preferably in the range of 10 to 1000 when converted to Reynolds number, and more preferably 20 to 500. When the Reynolds number is 10 or less, the amount of generated droplets is small. On the other hand, when the Reynolds number exceeds 1000, the period of alternating current that reaches a synchronous state exceeds several tens KHz, and it is difficult to maintain a stable state.

A significant advantage of the present invention over the conventional method is that the minimum voltage at which synchronization is obtained is much smaller than the conventional method. As described above, in the conventional method, a voltage of at least several hundred volts is required, and since the electric field concentrates on the hole portion of the nozzle where the insulating coating is not applied, this portion is easily corroded. In the method of the invention, not only a few volts may be required, but also the area of the conductive portion of the nozzle and the electrode is not particularly limited, so that the area can be widened, and this portion corrodes because the electric field is concentrated in the conductive portion. There is no such thing. Therefore, even when a voltage of several hundred volts or more is applied to the scale, corrosion of the nozzle or the electrode does not occur.

In the method of the present invention, it is difficult to form a uniform droplet at a high voltage required by the conventional electric method. Although the reason is not necessarily clear, it is considered that the self-excited vibration of the liquid column and the effect of concentrating the electric field on the hole (6) of the insulating plate are synergistic. Actually, liquid is formed in the vicinity of the hole (6).

As the voltage that changes at a constant cycle, a normal AC voltage can be used, but a voltage having a half-wave rectified waveform or a pulse-like voltage is preferable because the frequency and the voltage have a wider synchronization range. The applicable voltage varies depending on the type of the liquid and the dispersion medium, but is usually 3 to 2000 volts, preferably 5 to 50 volts.
0 volt, frequency is usually 0.3-20KHz, preferably 0.5-10
KHz.

The flow rate of the dispersion medium is preferably such that the concentration of the droplets in the dispersion is 5% by volume or less, and more preferably 3% by volume or less. By flowing the dispersion medium at such a flow rate, the droplets do not stay around the electrodes and do not recombine with each other or adhere to the electrodes, and the droplets flow from the droplet generation area with the dispersion medium. Left.

The uniform droplets obtained as described above are usually subjected to the additional treatment described above, and are converted into completely coagulated particles.

Next, the case where a vinyl polymerizable monomer liquid is used as a liquid instead of a solution of a polymer substance will be described.

In this case, the polymerizable monomer dispersed as uniform droplets in the dispersion medium in the same manner as described above is polymerized by a known suspension polymerization method to obtain uniform polymer particles. Since the dispersion may be either O / W type or W / O type, the monomer may be hydrophilic or hydrophobic. The vinyl polymerizable monomers may be used alone or in combination of two or more. A non-reactive diluent may be added to the vinyl polymerizable monomer liquid comprising such a monomer in order to adjust the structure of the obtained polymer particles. Specific examples of the diluent include, for example, aliphatic saturated hydrocarbons having 5 to 12 carbon atoms, aliphatic lower alcohols having 5 to 12 carbon atoms, such as benzene, diethylbenzene, xylene, and toluene.

Specific examples of the hydrophobic monomer include, for example, styrene, ethyl styrene, chloromethylated styrene, methyl acrylate, methyl methacrylate, acrylonitrile, maleic anhydride, monovinyl monomers such as vinyl acetate, divinylbenzene, ethylene glycol dimethacrylate, polyethylene Glycol dimethacrylate,
Examples include polyvinyl monomers such as diallyl phthalate. Of these, styrene-divinylbenzene, chloromethylated styrene-divinylbenzene, styrene-
Combinations of maleic anhydride-divinylbenzene, methyl methacrylate-divinylbenzene, methyl methacrylate-ethylene glycol dimethacrylate are particularly preferred. The polymerization of these monomer liquids is carried out by generating ultraviolet light or heat to generate free radicals in a polymerization initiator, for example, benzoyl peroxide or azobisisobutyronitrile, which has been previously added in a small amount.

Specific examples of the hydrophilic monomer include, for example, acrylamide, various alkyl acrylamides, hydroxyethyl methacrylate, acrylic acid, vinyl sulfonic acid,
N-vinylpyrrolidone and the like can be mentioned. Since these polymers are water-soluble, they are usually insolubilized by copolymerization with a crosslinking agent. Crosslinking agents include, for example, methylene bisacrylamide, polyethylene glycol dimethacrylate, and the like. Further, as a polymerization initiator, for example, hydrophilic ammonium persulfate is added.

The viscosity of the monomer liquid is 50 cps or less, preferably 20 cps or less, similarly to the above-mentioned solution of the polymer substance. Also,
There is no particular limitation on the electrical conductivity of this liquid.

When a hydrophobic monomer is used as the dispersion medium for these monomer liquids, a nonionic surfactant such as gelatin, methylcellulose, or polyvinyl alcohol is usually used in the same manner as the dispersion medium for the solution containing the polymer substance. ~
An aqueous solution to which about 5% is added is used.

Further, in the case of a hydrophilic monomer, for example, toluene, xylene, tetralin, ligroin,
Hydrocarbon solvents such as liquid paraffin, carbon tetrachloride, halides such as trichloroethylene, 1,1,2,2-trachloroethylene and chlorobenzene, vegetable oils such as castor oil and cottonseed oil, and silicone oils are used. These include surfactants having an HLB value of 3 to 6, such as sorbitan monooleate and glycerol monostearate.
0.5 to 5% is added.

Using this monomer liquid and dispersion medium, droplets are formed in synchronism with the voltage cycle that changes at a constant cycle of several to several thousand volts in the same manner as described above.

The uniform monomer droplets suspended in the dispersion medium in this manner can usually be further polymerized by heating or irradiation with ultraviolet rays to obtain uniform polymer particles for various purposes. Depending on the purpose of use, a treatment for introducing a physiologically active substance such as a hydrophilic group, an ion exchange group, and an antibody is further added.

As described above, according to the method of the present invention, fine uniform droplets having a droplet diameter of 20 to 250 μm can be stably obtained using a voltage much lower than that of the conventional method.

Next, the method of the present invention will be described more specifically with reference to examples. In the embodiment, water and kerosene are used as a combination of the droplet and the dispersion medium, but it is needless to say that the various combinations described above are possible.

Example 1 Kerosene (viscosity at room temperature is less than 1 cps and electric conductivity is 2 × 10 ⁻⁹ s / cm) containing 4% of a nonionic surfactant as a liquid for liquid droplets (dispersed phase) was used. Using distilled water (having an electric conductivity of 4.6 × 10 ⁻⁶ s / cm) as a dispersion medium, a uniform aqueous suspension of kerosene droplets was produced by the apparatus shown in FIG. 1 under the following conditions.

The nozzle (2) used was a stainless steel plate having a hole (3) having a diameter of 100 μm. This nozzle was not provided with any insulating coating as described in JP-A-58-175668. A hole (13) having a diameter of 10 mm was formed in the styrene steel electrode (11). An insulating plate (5) made of polytetrafluoroethylene having a thickness of 200 μm and having a hole (6) having a diameter of 400 μm was provided between the nozzle and the electrode. The distance between the nozzle (2) and the insulating plate (5) was 200 μm, and the distance between the nozzle (2) and the electrode (11) was 10 mm. These were fixed in a transparent acrylic resin container in the arrangement shown in FIG. Whether or not uniform droplets were generated was confirmed by observing while blinking a stroboscope from outside the transparent container. All experiments were performed at room temperature.

Kerosene was sent to the nozzle at 1.3 × 10 ⁻¹ ml / min. In addition, distilled water was supplied from the inlet (7) between the nozzle and the insulating plate at 4.2 ml /
Sent by min. When the AC cycle of the AC power supply (14) was set to 700 Hz and the applied voltage was gradually increased, the state became synchronized when the voltage reached 5.2 volts, and uniform droplets with a diameter of 180 μm were continuously obtained. . The current at this time is 1 μA, which is the measurement limit.
It was below. When the voltage was further increased and reached 400 volts, two large and small droplets began to be generated in one cycle, and it was impossible to form a uniform droplet above this voltage.

Example 2 A kerosene droplet was prepared using the same apparatus as in Example 1 except that the nozzle was changed to a nozzle having a diameter of 50 μm.

The flow rates of kerosene and distilled water were 7 × 10 ^-2 ml / min and
It was 4.2 ml / min. The AC cycle was set to 4000 Hz, and the applied voltage was gradually increased. When the voltage reached 5.8 volts, the liquid crystal became synchronized, and one uniform droplet (82 μm in diameter) was continuously formed in one cycle. When the voltage was further increased, a mixture of small and large droplets was generated at 540 volts, and it was impossible to form a uniform droplet at a voltage higher than 540 volts.

Example 3 The apparatus used in Example 1 was used under the following conditions to generate droplets of distilled water using kerosene as a dispersion medium.

The flow rates of water and kerosene were 3.2 × 10 ^-1 ml / min and 6.3, respectively.
ml / min. When the AC cycle was set to 1100 Hz and the applied voltage was gradually increased, the synchronous state was reached at 130 volts, and the synchronous state was broken at 2000 volts. The diameter of the resulting uniform droplet is
It was 210 μm.

[Effects of the Invention] In the method of the present invention, a synchronized state can be obtained at a very low voltage as compared with the conventional method, so that the nozzle does not corrode, and the droplet does not adhere to the nozzle or the electrode, and is uniform and fine. Liquid droplets can be stably manufactured for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of one embodiment of a dispersion apparatus used in the method of the present invention, FIG. 2 is a schematic sectional view showing the state of an electric field of the embodiment shown in FIG. 1, and FIG. FIG. 4 is a schematic cross-sectional view showing a state of an electric field in another embodiment of the dispersion apparatus used in the method. (Main symbols in the drawings) (1): Droplet (2): Nozzle (4): Dispersion medium (5): Insulating plate (6): Hole in insulating plate (11), (12): Electrode (14): AC source

Continued on the front page (72) Inventor Tamyuki Eguchi 5-14-5 Koeidai, Kita-ku, Kobe-shi, Hyogo (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/06

Claims (1)

(57) [Claims] A liquid ejection nozzle, an electric insulating plate provided with a passage hole for the liquid, and an electrode are arranged in this order in a dispersion medium,
A method of forming a uniform droplet, comprising: ejecting a liquid from a nozzle while applying a constant period of voltage between the nozzle and an electrode to generate a number of uniform droplets synchronized with the period of the voltage. .