JP2882669B2 - Method and apparatus for producing polymer fine particles having uniform particle size - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing polymer fine particles having a uniform particle size useful for various labeling materials, standard particles, diagnostic carriers, spacers for liquid crystal display elements, and the like. And its device.

(Prior Art) As methods for producing polymer fine particles, the following methods (1) to (4) have been conventionally proposed.

(1) A method of polymerizing addition polymerizable monomers by a suspension polymerization method to obtain polymer fine particles.

(2) A method of polymerizing an addition polymerizable monomer by an emulsion polymerization method to obtain polymer fine particles.

(3) The addition polymerizable monomer is placed in water and irradiated with ultrasonic waves or stirred at a high speed with a homogenizer or the like to form droplets of fine particles composed of the addition polymerizable monomer. To obtain polymer fine particles by polymerization in

(4) As a method inferred from the technology of the method for producing droplets disclosed in JP-A-58-175668, an addition-polymerizable monomer is ejected from a nozzle and an AC voltage is applied to apply the addition-polymerizable monomer. A method for producing polymer fine particles by generating droplets having a uniform particle size comprising: and polymerizing the droplets by an appropriate method.

(Problems to be Solved by the Invention) The method according to the above (1) has an advantage that polymer particles having a wide particle size range can be obtained by adjusting the polymerization conditions. Is not uniform. In order to obtain polymer fine particles having a uniform particle size, it is necessary to classify after the completion of polymerization, and there is a disadvantage that the process becomes complicated.

In the method according to the above (2), the particle size of the obtained polymer fine particles is relatively uniform, but there is a drawback that polymer fine particles having a particle size of 0.3 μm or more cannot be obtained. Since the emulsifier is contained, the polymer fine particles cannot be produced in a pure state, or require a complicated process for removing the emulsifier.

In the method according to the above (3), the frequency, intensity,
By changing the processing time and the like, and changing the number of revolutions, strength and processing time of high-speed stirring, it is possible to easily obtain polymer fine particles having a wide range of particle diameters in the same manner as in the above method (1). It is possible. However, the obtained polymer fine particles are not uniform in particle size, and eventually have the same disadvantage as (1).

In the method according to the above (4), in order to obtain polymer fine particles having a desired particle size, it is necessary to change the AC frequency and voltage applied between the electrodes over a very wide range. A very special and expensive transformer with function is required, and this method requires one transformer per AC cycle.
Only a single uniform liquid is generated, and it takes considerable time to obtain a large number of uniform droplets. Therefore, the method according to (4) is disadvantageous for industrial production.

By the way, Watanabe et al. Have studied a method of producing uniform droplets by a DC voltage as a method of producing droplets, not a method of producing polymer fine particles (Journal of Colloid).
and Interface Science, 64 , 278-289 (1978)).

This method will be described in detail with reference to FIG. An apparatus for generating droplets used in this method includes a liquid tank 19 for storing a first liquid 18, an electrode 17 disposed in the liquid tank 19, a nozzle 15 formed of an electrically insulating material, It has an electrode 16 disposed in the nozzle 15, a micro feeder 11 for supplying the second liquid to the nozzle 15, and a DC power supply 20 for applying a DC voltage between the electrodes 16, 17. doing. In the figure, 13 is the second liquid sent from the micro feeder 11 to the nozzle 15
12 is a flow meter showing a supply amount of 12.

In the method for producing droplets by the DC voltage, an electrically insulating oil is used as the first liquid 18 and the second liquid 12
An aqueous solution containing an electrolyte is used. That is, in this method, in order to generate droplets having a uniform particle diameter, a necessary DC voltage is applied at a position where the second liquid 12 is ejected from the nozzle 15 (portion 15a in FIG. 2). Therefore, an electrolyte is added to the second liquid 12 in order to increase the electric conductivity of the second liquid 12. Therefore, according to this method, there is a disadvantage that the generated droplet contains impurities, and further, since the droplet is generated by water-in-oil,
It is not possible to produce polymer fine particles composed of an addition-polymerizable monomer.

An object of the present invention is to solve the above-mentioned drawbacks, and an object of the present invention is to provide a manufacturing method and an apparatus capable of easily manufacturing polymer fine particles having a uniform particle diameter in a wide particle diameter range. Still another object of the present invention is to provide a method and an apparatus for producing polymer fine particles containing no impurities.

(Means for Solving the Problems) According to the method for producing polymer fine particles having a uniform particle size of the present invention, a second liquid containing an addition-polymerizable monomer is placed in a liquid tank containing a first liquid. In addition to providing a nozzle capable of jetting, an electrode is provided in the liquid tank, and the first liquid is made of water or an aqueous solution that does not dissolve the second liquid and contains substantially no electrolyte. Applying a DC voltage between the nozzles, ejecting the second liquid from the nozzle tip into the first liquid, and polymerizing the addition polymerizable monomer in the droplet generated from the second liquid. It achieves the above object.

In the apparatus for producing polymer fine particles having a uniform particle size according to the present invention, the first liquid composed of water or an aqueous solution in which the second liquid containing the addition-polymerizable monomer is not dissolved and contains substantially no electrolyte is used. A liquid tank to be filled, a second liquid ejection nozzle provided in the liquid tank and formed of a conductive member, an electrode, and a DC power supply for applying a DC voltage between the nozzle and the electrode. , And a droplet generating apparatus having the above-mentioned configuration, and the above object is achieved.

FIG. 1 shows an example of an apparatus for producing droplets constituting a production apparatus of the present invention, and the method for producing polymer fine particles having a uniform particle size of the present invention will be described with reference to this apparatus.

The liquid droplet generating device is provided at a liquid tank 7 in which the second liquid containing the addition-polymerizable monomer is not dissolved and the first liquid having low electric conductivity is contained, and is disposed at the bottom of the liquid tank 7. A second liquid ejection nozzle 5 formed of a conductive member,
A DC power supply for applying a DC voltage between the nozzle 5 and the liquid tank 7 (electrode), a mig feeder 1 for supplying an addition polymerizable monomer to the nozzle 5, and a connecting pipe 4 for connecting the nozzle 5 and the micro feeder 1 And a flow meter 3 provided in the apparatus.

The material forming the nozzle 5 may be any material having conductivity, and for example, a stainless steel tube is used. The inner diameter of the nozzle 5 is usually 30 to 300 μm, and particularly preferably 50 to 200. For example, an electrically insulating cylinder 5b is provided around the nozzle 5 and is electrically insulated from the liquid tank 7. The nozzle 5 protrudes from the bottom of the liquid tank 7 in the vertical direction, and a spout 5a is provided at the tip. Further, as shown in FIG. 2, the nozzle 5 may be provided from above the liquid surface to below. Thus, the nozzle 5 is electrically connected to the DC power supply, but is electrically insulated and coated except for the tip. In addition, the liquid tank 7 may be formed of a conductive member as an electrode as described above, or an electrode of another member may be provided in the liquid tank 7. In this case, the liquid tank 7 may be formed of an insulating member. The shape of the electrode provided in the liquid tank 7 can be changed as appropriate, and for example, is formed of a ring member or a net having a hole for passing a droplet in the center portion, a U-shaped member in a plan view, or a U-shaped member. May be.

Here, the relationship between the nozzle 5 and the polarity of the electrode is important. That is, in the present invention, it is preferable that the nozzle 5 has a negative polarity and the electrode has a positive polarity. This is because the current value increases linearly as the applied voltage is increased, but when a voltage of the same magnitude is applied between the nozzle 5 and the electrode, the voltage becomes negative when the nozzle 5 is positive. This is because a current several times larger than that in the case where the current flows. As described above, when a high voltage is applied with the nozzle 5 having a positive polarity, a larger amount of current flows and the nozzle 5 is damaged, and the practicality is significantly reduced.

Next, the first liquid 6 and the second liquid 2 used in the present invention will be described.

The first liquid 6 has a low electric conductivity and is made of a liquid that is incompatible with the second liquid 2.
When the liquid 2 is ejected from the nozzle 5 as a droplet, it is preferable that the liquid 2 can be dispersed uniformly and without coalescing.

For this purpose, for example, distilled water and ion-exchanged water are suitable. In addition, a nonionic surfactant or a suspension stabilizer is added to the first liquid 6 to uniformly disperse the droplets in the first liquid 6 and promote the action of preventing coalescence of the droplets. May be. However, these substances must be capable of dissolving in the first liquid 6 and satisfy the two conditions of not increasing the electric conductivity of the first liquid 6. The electric conductivity of these first liquids 6 is
It is preferably 100 micro Siemens or less per 100 cm (100 μS / cm), and more preferably 10 μS / cm or less.

Examples of the nonionic surfactant include polyethylene oxide laurate, polyethylene oxide palmitate, polyethylene oxide stearate, polyethylene oxide oleate, polyethylene oxide lauryl ether, polyethylene oxide cetyl ether, polyethylene oxide oleyl ether, polyethylene oxide stearyl ether, and polyethylene oxide. Dodecyl ether, polyethylene oxide octyl phenol ether, polyethylene oxide nonyl phenol ether, sorbitan monolaurate,
Sorbitan monomyristate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, sorbitan monobehenate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, Polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyglycerin monoisostearate, diglycerin monolaurate and the like are preferably used.

Examples of the suspension stabilizer include polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, polyvinyl methyl ether, polyacrylamide, polydiallylamine, polyethyleneimine, carboxymethyl cellulose, methyl cellulose, methyl hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, Gum arabic, gum tragacanth, gum karaya, guar gum, cod gum, propylene glycol alginate, xanthan gum, soluble starch, dialdehyde starch, dextrin, British gum, acetyl starch, carboxymethyl starch, hydroxyethyl starch, hydroxypropyl starch, etc. are preferably used. You.

The viscosity of the first liquid 6 at 25 ° C. is preferably 60 cps or less. If the viscosity is 60 cps or more, the electric energy acting on the tip of the nozzle 5 is weakened, which causes a loss of the uniformity of the droplet diameter.

The second liquid 2 is a liquid containing an addition polymerizable monomer, and may contain an addition polymerizable monomer and a polymerization initiator. The addition polymerizable monomer and the polymerization initiator used must be insoluble in water and compatible with each other.

The addition polymerizable monomer used in the present invention is usually a liquid at normal temperature and normal pressure, but may be a gas which liquefies under a slight pressure. Examples of the addition polymerizable monomer include vinyl chloride, vinylidene chloride, vinyl bromide, vinyl acetate, styrene, divinylbenzene, chlorostyrene, methyl vinyl ether, butadiene, chloroprene, methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. , Methyl methacrylate, butyl methacrylate, isobutyl methacrylate, acrylonitrile, methacrylonitrile, methyl glycidyl methacrylate, and the like are preferably used.

The viscosity of the second liquid 2 at 25 ° C. is preferably 50 cps or less. This is because if the viscosity is 50 cps or more, coalescence of the droplets is likely to occur near the tip of the nozzle 5, which causes a loss of the uniformity of the particle diameter of the droplets.

The addition polymerizable monomer used in the present invention may be used alone, or two or more kinds may be used. In addition, it is often the case that a polymerization initiator coexists with such an addition-polymerizable monomer to form uniform droplets, but it is not always necessary to coexist a polymerization initiator. This is because, depending on the type of the addition-polymerizable monomer, the polymer may be polymerized by heat, light, radiation, or the like under conditions in which no polymerization initiator is present to form polymer fine particles.

The polymerization initiator is generally a substance that generates a radical by heat or light. Examples of the polymerization initiator include benzoyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, tertiary butyl peroxide, acetyl peroxide, isobutyryl peroxide, tertiary butyl hydroperoxide, cumene hydroperoxide. Peroxide, diisopropyl peroxy dicarbonate, tertiary butyl peroxy benzoate, 2,
2'-azobisisobutyronitrile, dimethyl-2,2'-
Azobisisobutyronitrile, 2,2'-azobis (2,4-
Dimethyl valeronitrile), benzoin, dibenzoyl, benzoin ethyl ether, benzoin isobutyl ether and the like can be suitably used.

In order to generate droplets using the above-described apparatus, a DC voltage is applied between the nozzle 5 and the liquid tank 7, and the second liquid 2 is supplied to the nozzle 5 from the micro feeder 1 in this state. The second liquid 2 is ejected from the tip of the nozzle 5 into the first liquid 6. The specific gravity of the second liquid 2 is the first liquid 6
, The second liquid 2 rises in the first liquid 6 as droplets. Here, the particle size of the droplet is
It can be adjusted by the type and temperature of each liquid component to be used, the viscosity of each liquid, and the value of the DC voltage applied between the nozzle 5 and the liquid tank 7. The diameter tends to decrease. The DC voltage is usually 30
0V to 3000V.

Thereafter, the addition polymerizable monomer in the obtained droplet is polymerized to obtain polymer fine particles. Polymerization of the addition-polymerizable monomer can be carried out, for example, by transferring the droplets to another reaction vessel and heating, or irradiating light or radiation.

The particle size of the polymer fine particles thus obtained is usually 0.05μ.
m to 500 μm, more typically 0.2 μm to 200 μm
m. If the conditions for forming the droplets are set, droplets having a uniform particle size are generated, so that fine polymer particles having a uniform particle size and a narrow particle size distribution can be obtained. Since the volume contraction occurs when the droplet of the addition-polymerizable monomer is polymerized, the particle size of the droplet is preferably set to be larger than the desired particle size of the fine particles so as to compensate for the above-described decrease due to the contraction.

(Examples) Hereinafter, the present invention will be described based on examples.

Example 1 The same apparatus as in FIG. 1 was used, except that a perforated metal disk was provided as an electrode facing the nozzle (therefore, the liquid tank 7 was not grounded). Uniform droplets of styrene were generated and polymerized to obtain polystyrene fine particles having a uniform particle size.

Distilled water containing 1% by weight of polyvinyl alcohol is charged into the liquid tank, while a styrene monomer containing 1% by weight of benzoyl peroxide is charged as a polymerization initiator in the microfeeder, and the mixture is supplied to the nozzle at a flow rate of 0.5 m ≒ / min. Supplied. When a DC voltage of 2000 V was applied between the nozzle and the liquid tank, uniform droplets of styrene monomer were generated in distilled water in the liquid tank. When the particle diameters of a large number of generated droplets were measured, they were about 0.95 μm and uniform. The droplets of the styrene monomer were transferred to a glass polymerization vessel and polymerized at 80 ° C. for 6 hours. The obtained polystyrene fine particles had an average particle diameter of 0.90 μm and a standard deviation of the particle diameter of 0.06 μm, and were extremely uniform in particle diameter.

Example 2 Using the apparatus shown in FIG. 1, uniform droplets of methyl methacrylate were generated by the method described below, and polymerized to obtain polymethyl methacrylate fine particles having a uniform particle size.

Distilled water is put into the liquid tank, while 2,2'-azobisisobutyronitrile 2 is used as a polymerization initiator in the micro feeder.
Methyl methacrylate monomer containing% by weight was charged and fed to the nozzle at a flow rate of 0.9 ml / min. When a DC voltage of 1700 V was applied between the nozzle and the liquid tank, uniform droplets of methyl methacrylate monomer were generated in distilled water. When measuring the particle size of many generated droplets, about 2.6μ
m. The droplets of the methyl methacrylate monomer were transferred to a glass-made polymerization vessel, and polymerized at 70 ° C. for 8 hours.

The obtained fine particles of polymethyl methacrylate had an average particle size of 2.45 μm and a standard deviation of the particle size of 0.10 μm, and were extremely uniform in particle size.

Example 3 Using the apparatus shown in FIG. 1, uniform droplets of styrene and methyl methacrylate were generated by the method described below, and polymerized to form fine particles of a copolymer of styrene and methyl methacrylate having a uniform particle size. I got

The liquid tank is filled with distilled water containing 1.5% by weight of polyethylene oxide stearate, while the microfeeder is a 1: 1 molar ratio of a styrene monomer containing 1.5% by weight of tertiary butyl hydroperoxide as a polymerization initiator to a methyl methacrylate monomer. Was supplied to the nozzle at a flow rate of 0.7 m ≒ / min. When a DC voltage of 1500 V was applied between the nozzle and the liquid tank, droplets of both monomer mixtures were formed in distilled water in the liquid tank. When the particle diameters of a large number of generated droplets were measured, they were about 3.1 μm and uniform. The droplets of the monomer mixture were transferred to a glass polymerization vessel and polymerized at 75 ° C. for 7 hours.

The obtained copolymer of styrene and methyl methacrylate contains 55% of styrene and 45% of methyl methacrylate in a molar ratio, has an average particle size of 1.05 μm, a standard deviation of the particle size of 0.06 μm, and has an extremely large particle size. It was uniform.

(Effect of the Invention) In the method for producing polymer fine particles of the present invention, the second liquid containing the addition-polymerizable monomer is added to the first liquid from the tip of the nozzle while applying a DC voltage between the electrode and the nozzle. Therefore, the particle size range of the droplet containing the addition polymerizable monomer can be arbitrarily controlled, and the particle size of the droplet can be controlled only by an electrical factor such as a voltage. Therefore, compared to the method of controlling the particle size by a chemical factor, which is performed by many conventional techniques, droplets having a narrow particle size distribution and a uniform particle size can be generated by a reliable and simple operation. As a result, when polymerizing the addition polymerizable monomer in the droplet, polymer fine particles having a uniform particle size can be extremely easily produced at an arbitrary particle size.
It is extremely excellent as a method for manufacturing a spacer for a liquid crystal display element.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of the production apparatus of the present invention, and FIG. 2 is a schematic view showing a conventional droplet generation apparatus. DESCRIPTION OF SYMBOLS 1 ... Micro feeder, 2 ... Second liquid, 5 ... Nozzle, 6 ... First liquid, 7 ... Liquid tank, 8 ... DC power supply.

Claims (2)

(57) [Claims] A nozzle capable of ejecting a second liquid containing an addition-polymerizable monomer is provided in a liquid tank containing a first liquid, and an electrode is provided in the liquid tank. Is composed of water or an aqueous solution that does not dissolve the second liquid and contains substantially no electrolyte, applies a DC voltage between the electrode and the nozzle, and removes the second liquid from the tip of the nozzle. A method for producing high-molecular fine particles having a uniform particle diameter, which comprises jetting into a first liquid and polymerizing an addition-polymerizable monomer in a droplet generated from a second liquid. 2. A liquid tank in which a second liquid containing an addition polymerizable monomer is not dissolved and a first liquid composed of water or an aqueous solution substantially containing no electrolyte is placed. A droplet generation apparatus includes a second liquid ejection nozzle formed of a conductive member, the electrode being provided, and a DC power supply for applying a DC voltage between the nozzle and the electrode. An apparatus for producing polymer fine particles having a uniform particle size.