JPH06145207A - Production of singly dispersed polymer beads - Google Patents

Abstract

PURPOSE:To produce polymer beads having an uniform size in a simple operation by the use of a simple device by filling an aqueous dispersion medium in a stirring type polymerizer equipped with a specific stirring blade, feeding the drops of a polymerizable polymer solution, and polymerizing the polymerizable substance with stirring. CONSTITUTION:An aqueous dispersion medium is filled in a stirring type polymerizer in a range capable of being stirred, and the drops of a polymerizable substance solution formed through an orifice plate are fed into the polymerizer and polymerized with agitation to produce the singly dispersed polymer beans. The stirring type polymerizer has a lattice blade 3 having a bottom paddle 2 or plural parallel blades having mutually crossing surface directions in the vertical direction on its stirring shaft. The orifice plate is arranged in the polymerizer, especially at its bottom, and the plate is placed in a solution drop-producing device having discharging ports capable of feeding the drops of the polymerizable solution. The solution drops are formed in the form of a drop group synchronized with vibration by passing the polymerizable solution through the orifice plate and subsequently giving the vibration to the produced liquid column having a laminar flow property. The stirring is performed at a blade tip velocity of 0.1-2.0m/s.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing monodisperse polymer beads.

[0002]

2. Description of the Related Art As a conventional method for producing monodisperse polymer beads, there is a method in which a polymerizable liquid is made into droplets and the droplets are polymerized in a polymerization reactor.

A method of forming a droplet of a polymerizable liquid is, for example, a polymerizable liquid having a laminar flow characteristic is jetted into an aqueous dispersion medium through an opening of an orifice plate, and the jet flow is vibratingly excited to form the polymerizable liquid. A method of generating droplets is known (Japanese Patent Publication No. 1-28761 and Japanese Patent Publication No. 2-25).
922).

The method of polymerizing the droplets in a polymerization reactor is, for example, in the first reactor in the form of a column, by the floating force of the polymerizable droplets and the downward flow of the aqueous dispersion medium While maintaining the fluidized bed state, the polymerization is advanced until the specific gravity of the polymerizable droplets becomes close to the specific gravity of the aqueous dispersion medium, and the polymerizable droplets having reached the specific gravity are used to accompany the downward flow of the aqueous dispersion medium. Then, it is transferred from the bottom of the first reactor to the droplet separator through the conduit, and the polymerizable droplets that have not reached the specific gravity of the aqueous dispersion medium flow downward from the droplet separator through the conduit to the downward direction of the first reactor. It is returned to the first reactor by being entrained in an aqueous dispersion medium that is circulated as a liquid, and polymerization is further progressed. Through the column-shaped second reactor, and the upper part of the second reactor Luo and through conduit an aqueous dispersion medium is circulated through the separation tube disposed in the second reactor bottom, by previously to form an upward flow of aqueous dispersion medium in the separation pipe,
The polymerizable droplets transferred to the second reactor were kept in a fluidized bed in the second reactor until reaching a predetermined polymerization conversion rate that settles against the upward flow, and reached a predetermined polymerization conversion rate. A continuous suspension polymerization method (Japanese Patent Publication No. 25925/1990) in which polymer particles are taken out from the bottom of the separation tube by utilizing the fact that the polymer particles settle at the bottom of the separation tube, and paddle blades, gate blades, anchors A method (Japanese Patent Publication No. 1-29483) using a stirring type polymerization machine equipped with a blade, a loop blade, an egg beater blade or the like as a stirring blade is known.

Further, as the agitator, a bottom paddle is attached to the agitation shaft, and a lattice blade composed of an arm portion and a strip extending in a direction perpendicular to the arm portion is attached to a portion above the bottom paddle (Japanese Patent Publication No. 1-37173
No.), and two flat blades located above and below and intersecting with each other in the plane direction are attached to the stirring shaft (Abstracts of Summer Seminar P22 of the Society for Chemical Engineering, 1991, Technical Committee on Mixing Technology). There is.

[0006]

The above-mentioned conventional method for producing monodisperse polymer beads has the following problems in the step of polymerizing polymerizable droplets in a polymerization reactor. That is, the method using the column-shaped first and second reactors has a problem in that the steps are complicated, an economical burden is increased in industrialization, and the operation is complicated. Also, paddle wings, gate wings,
The method using a stirring blade such as an anchor blade, a loop blade, or an egg beater blade maintains the required power required to uniformly disperse the droplets, and it is difficult to suppress the stirring shear force to the extent that the droplets are not split. Therefore, there is a problem that polymer beads having a uniform size cannot be obtained in a high yield.

The present invention has been made in order to solve the above problems, and a method for producing monodisperse polymer beads capable of producing polymer beads having a uniform size by a simple operation using a simple device. Is to provide.

[0008]

According to the present invention, there is provided a stirrer-type polymerization machine equipped with, as stirrer blades, a latticed blade having a bottom paddle on a stirring shaft or a plurality of flat plate blades positioned vertically and having plane directions intersecting each other. A monodisperse polymer bead is prepared by filling an aqueous dispersion medium within a stirrable range with a stirring blade, and supplying a droplet of a polymerizable liquid formed through an orifice plate to polymerize while stirring. A method of making dispersed polymer beads is provided.

The present invention solves the above problems by using a specific stirring blade. In the present invention, there is used a stirring type polymerization machine provided with a stirring blade equipped with a lattice blade having a bottom paddle on the stirring shaft or a plurality of flat blade blades which are vertically arranged and whose plane directions intersect each other as stirring blades.

A stirrer having a stirring shaft fitted with a lattice blade having a bottom paddle is composed of, for example, a stirring shaft 1, a bottom paddle 2 and a lattice blade 3 as shown in FIG. The lattice blade 3 is composed of a plate rod-shaped arm portion 4 extending in the tank radial direction and a plate rod-shaped strip portion 5 extending in a direction perpendicular to the arm portion, and has at least two openings. The bottom paddle has the property of discharging the liquid in the radial direction, and the lattice blade has the property of shearing the liquid and subdividing it, and mixing the liquid subdivided by the minute vortex generated on the rear side. .

The blade diameter d is d / D = 0.
The range of 4-0.8 is preferable, and 0.5-0.7 is more preferable. The lattice width H1 is H1 / H with respect to the width H of the entire blade.
= 0.5 to 0.9 is preferable, and 0.6 to 0.8 is more preferable. Bottom paddle width H2 is H2 / H
The range of H = 0.1-0.5 is preferable, and 0.2-0.4
Is more preferable. H / d = 0.5 to 5.0 is preferable, and 1.0 to 3.0 is more preferable.

A stirrer equipped with a plurality of flat plate blades which are vertically arranged on the stirring shaft and whose surface directions intersect with each other is composed of a stirring shaft 1 and a flat plate blade 6 as shown in FIG. 2, for example. The flat plate blade is composed of two or more stages located above and below, preferably 2 to 5 stages. The plane directions of the flat blades intersect with each other, and the intersecting angle is 10 to 90 °, preferably 30 to 70 °. Further, as shown in FIG. 3, the flat blade located in the upper stage may be provided with a plate-shaped fin for extending the blade tip downward, and the lower blade may be provided with a backward paddle as shown in FIG. May be.

The blade diameter d is d / D = 0.
The range of 4-0.8 is preferable, and 0.5-0.7 is more preferable. Further, H / d = 0.5 to 5.0 is preferable, and 1.
0 to 3.0 is more preferable.

The stirring conditions in the polymerization tank are defined by the stirring blade tip speed and the required stirring power, and the stirring blade tip speed is preferably in the range of 0.1 to 2.0 m / s, and in the range of 0.2 to
1.0 m / s is more preferable. If it exceeds 2.0 m / s, the particles will be broken by the shearing force, and if it is less than 0.1 m / s, the mixing will be insufficient.

The power Pv required for stirring is the volume V of the polymerization tank, the diameter d of the stirring blade, the rotation number n of stirring, the density ρ of the liquid, and the viscosity μ of the liquid.
And the function N of the geometric shape of the stirring tank, stirring blades, etc. Pv = N · ρ · n ³ · d ⁵ / V

The power required for stirring in the present invention is 0.01
To 0.5 kW / m ³ is preferable, and 0.01 kW /
If it is less than m ³ , the coalescence of the droplets occurs due to insufficient stirring power, and if it exceeds 0.5 kW / m ³ , the stirring is too strong and the particles are broken, which is not preferable.

In the present invention, droplets of the polymerizable liquid formed through the orifice plate are supplied to the stirring type polymerization machine. The orifice plate may be arranged at the bottom of the stirring type polymerization machine, but it is arranged in the droplet generating device having an outlet capable of supplying droplets of the polymerizable liquid to the stirring type polymerization machine. You may.

The orifice plate is provided with one or more holes, and the material of the plate, the arrangement of the holes, and the number of holes are not particularly limited. The pore size of the orifice plate is determined primarily by the desired particle size of the polymer beads. Usually, the desired particle size of the polymer beads is 10 to 10,000 μm, and in order to produce a polymer of this size, the physical properties of the monomer,
Orifice plates with a pore size of 5 to 5000 μm are usually used, depending on various factors for forming droplets including the physical properties of the continuous phase and the vibration conditions. If it is less than 5 μm, it is difficult to process, and the precision is deteriorated.

By passing the polymerizable liquid through the orifice plate, a liquid column of the polymerizable liquid having a laminar flow property can be formed.

The formation of the liquid column of the polymerizable liquid having the laminar flow property is defined by the Reynolds number Re. This Reynolds number is represented by the following equation by the density ρ of droplets formed into droplets, the viscosity μ, the velocity u of the liquid jet, and the orifice hole diameter D. Re = D · u · ρ / μ

The Reynolds number of the polymerizable liquid in the present invention is preferably in the range of 20 to 2000 in view of the laminar flow characteristics of the liquid jet. If it is less than 20, the productivity will be reduced, and if it exceeds 2000, a turbulent flow region will result and uniform droplet groups will not be generated, which is not preferable.

In the present invention, vibration may be applied to the orifice plate or the liquid column of the polymerizable liquid when forming the droplets of the polymerizable liquid. By applying vibration to the liquid column, it is possible to form droplet groups that are synchronized with the cycle of vibration.

The vibration is suitably performed by any means that vibrates in a vibrational characteristic such that the liquid jet is divided into droplets of uniform diameter. Generally 10 to 50000 Hz
A frequency of gives the desired vibration characteristic. As the vibrating means, a piezoelectric oscillator, a mechanical oscillator, an electroacoustic oscillator, a hydroacoustic oscillator, an electromagnetic oscillator, a magnetoresistive transducer, or the like can be used. These vibrating means are attached to, for example, a passage wall of the polymerizable liquid on the entrance side of the orifice plate.

The aqueous dispersion medium used in the present invention is not particularly limited, but water is preferable, and a water-soluble organic solvent such as methanol or acetone may be allowed to coexist. Further, although the aqueous medium contains a dispersion stabilizer, those generally used in suspension polymerization can be used. For example, gelatin, polyvinyl alcohol, starch, polyacrylic acid-based salts,
Alternatively, it is a water-insoluble inorganic compound such as magnesium silicate or a cellulose ether such as carboxymethyl methyl cellulose or hydroxyethyl cellulose.

In the present invention, an agitating polymerization machine is first charged with an aqueous dispersion medium, and then the polymerizable liquid is supplied in a droplet state. Therefore, the liquid volume in the polymerization machine increases with the supply of the polymerizable droplets.

The amount of the aqueous dispersion medium charged may be such that the liquid level is 0.1 H or more from the lower end of the blade. Preferably 0.2-
It is 0.9H.

In the present invention, the polymerization may be started at the same time when the supply of the polymerizable droplets is started, and after the supply of the polymerizable monomer is completed,
Polymerization may be initiated. The liquid level when the total amount of the aqueous dispersion medium and the polymerizable droplets is charged may be 0.2H or more from the lower end of the blade, and more preferably 0.3H or more.

The polymerizable liquid comprises a polymerizable monomer and a polymerization initiator, and can be diluted with a solvent if necessary. The polymerizable monomer is not limited, for example, styrene and its derivatives, ethylenically unsaturated monoolefins, vinyl halides, organic acid vinyl esters,
Methacrylic acid esters, acrylic acid esters, vinyl ethers, vinyl ketones and the like can be used. Specifically, styrene, O-methylstyrene, m-
Methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene,
3,4-dichlorostyrene, p-ethylstyrene, 2,
4-dimethylstyrene, pn-butylstyrene, p-
tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, ethylene, propylene,
Butylene, isobutylene, vinyl chloride, vinylidene chloride, butyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n methacrylate -Octyl, dodecyl methacrylate, lauryl methacrylate, stearyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, acrylic acid n-
Butyl, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, chloroethyl acrylate,
Examples include phenyl acrylate, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone.

Examples of the polymerization initiator include, but are not limited to, monomer-soluble free radical polymerization initiators such as peroxygen compounds, for example, benzoyl peroxide or azobisisobutyronitrile, hydroperoxide and the like.

The solvent is not particularly limited as long as it dissolves the monomer and the polymerization initiator, and for example, toluene,
Hexane and the like are exemplified. The polymerization temperature is usually 50
~ 90 ° C.

[0031]

A stirring blade selected from a lattice blade having a bottom paddle on the stirring shaft or a plurality of flat blade blades positioned vertically and intersecting with each other in the radial direction discharges the aqueous dispersion medium containing the polymerizable droplets in the radial direction. Along with this, the polymerizable liquid droplets are uniformly dispersed so as not to break up by being shredded and subdivided by minute vortices generated on the rear side of the blade.

[0032]

EXAMPLES Examples will be described below. Here, the average particle diameter is a volume average diameter measured by COULTER LS 130 (manufactured by COULTER ELECTRONICS, INC; laser diffraction method). The monodispersity was evaluated by the dispersion coefficient. Here, the dispersion coefficient is represented by the following formula (standard deviation σ / average particle diameter) × 100 (%)

Example 1 A monomer solution (lauryl methacrylate / vinyl acetate / divinylbenzene / lauroyl peroxide = 80) was placed in a droplet generator filled with a 1 wt% PVA solution.
/ 10/9/1) droplet groups were generated. The droplet generation device is arranged below the polymerization tank. 8 orifice holes
The holes have a pitch width of 1.5 mm and the hole diameter is 80 μm. 0.4g / m / monomer solution per orifice
At a flow rate of in, it was jetted into the continuous phase to generate droplets, which were continuously discharged and supplied to the polymerization tank.

The polymerization tank volume is 20 L, and the stirring blade has a blade diameter of 140.
mm, 250 mm wide, with a bottom paddle (Fig. 1)
It was used. d / D is 0.55, H ₂ / H is 0.35, and the initial amount of the aqueous dispersion medium charged is 0.
6H, 0.8H at the end of monomer supply. Stirring speed 80 rpm (blade tip speed 0.59 m / s) Temperature 8
Polymerization was carried out at 0 ° C, resulting in an average particle diameter of 260μ.
A monodisperse polymer having m and a dispersion coefficient of 13% was obtained.

Example 2 A monomer solution (lauryl methacrylate / vinyl acetate / divinylbenzene / lauroyl peroxide = 80) was placed in a droplet generator filled with a 1 wt% PVA solution.
/ 10/9/1) droplet groups were generated. The droplet generation device is arranged in the lower part of the polymerization tank and is equipped with a piezoelectric vibrator. The number of orifice holes is 8 and the pitch width is 1.5 mm.
The pore size is 80 μm. The monomer solution was jetted into the continuous phase from the orifice holes at a flow rate of 1.0 g / min per hole, and a sine wave vibration of 2600 Hz was applied. The generated droplets were continuously discharged from the upper portion of the droplet generator and supplied to the polymerization tank.

The same polymerization tank and stirring blade as in Example 1 were used, and the polymerization was carried out under the same conditions. As a result, the average particle diameter was 22.
A monodisperse polymer of 0 μm and a dispersion coefficient of 5.0% was obtained.

Example 3 A monomer solution (lauryl methacrylate / vinyl acetate / divinylbenzene / lauroyl peroxide = 80) was placed in a droplet generator filled with a 1 wt% PVA solution.
/ 10/9/1) droplet groups were generated. The droplet generation device is arranged in the lower part of the polymerization tank and is equipped with a piezoelectric vibrator. Number of orifice holes is 432, pitch width is 1.5m
m and the pore size is 80 μm. The monomer solution was jetted into the continuous phase from the orifice holes at a flow rate of 1.0 g / min per hole, and a sine wave vibration of 1900 Hz was applied. The generated droplets were continuously discharged from the upper portion of the droplet generator and supplied to the polymerization tank.

The polymerization tank volume is 200 L, and the stirring blade has a blade diameter of 30.
2 mm flat blades with a width of 0 mm and a width of 200 mm at a crossing angle of 45
A column combination (FIG. 2) was used. d / D is 0.
6, the initial amount of the aqueous dispersion medium charged was 0.6H at the liquid level, and the liquid level at the end of the monomer supply was 0.8H. Polymerization was carried out under conditions of a stirring rotation speed of 40 rpm (blade tip speed of 0.68 m / s) and a temperature of 80 ° C., resulting in an average particle diameter of 260 μ.
A monodisperse polymer having m and a dispersion coefficient of 8% was obtained.

Example 4 A monomer solution (lauryl methacrylate / vinyl acetate / divinylbenzene / lauroyl peroxide = 80/1) was introduced into the polymerization tank through an orifice plate provided at the bottom of the polymerization tank.
0/9/1) droplet groups were generated. The number of orifice holes is 8, the pitch width is 1.5 mm, and the hole diameter is 80 μm.
Vibration of a sine wave of 1100 Hz was applied by a piezoelectric vibrator.

The same polymerization tank and stirring blade as in Example 1 were used, and the polymerization was carried out under the same conditions. As a result, the average particle diameter was 30.
A monodisperse polymer of 0 μm and a dispersion coefficient of 8% was obtained.

Comparative Example A monomer solution (lauryl methacrylate / vinyl acetate / divinylbenzene / lauroyl peroxide = 80) was placed in a droplet generator filled with a 1 wt% PVA solution.
/ 10/9/1) droplet groups were generated. The droplet generation device is arranged in the lower part of the polymerization tank and is equipped with a piezoelectric vibrator. The number of orifice holes is 8 and the pitch width is 1.5 mm.
The pore size is 80 μm. The monomer solution was jetted into the continuous phase from the orifice holes at a flow rate of 1.0 g / min per hole, and was given a sine wave vibration of 2600 Hz. The generated droplets were continuously discharged from the upper portion of the droplet generator and supplied to the polymerization tank.

The polymerization tank volume is 20 L, and the stirring blade has a blade diameter of 140.
Anchor blades having a width of 100 mm and a width of 100 mm were used. Polymerization was carried out under the conditions of stirring rotation 80 rpm (blade tip speed 0.59 m / s) and temperature 80 ° C., resulting in an average particle diameter of 260 μm and a dispersion coefficient of 25%, and the monodispersity was worse than that obtained in Examples 1 to 3. became. In addition, a larger amount of aggregate was generated as compared with the case of the stirring blade used in Examples 1 to 3.

[0043]

According to the present invention, with a simple device,
Polymer beads having a uniform size can be produced by a simple operation.

[Brief description of drawings]

FIG. 1 is a schematic view of a stirring blade used in an embodiment of the present invention.

FIG. 2 is a schematic diagram of a stirring blade used in an example of the present invention.

FIG. 3 is a schematic view of a stirring blade according to another embodiment of the present invention.

FIG. 4 is a schematic view of a stirring blade according to another embodiment of the present invention.

[Explanation of symbols]

 1 Stirring shaft 2 Bottom paddle 3 Lattice blade 4 Arm portion 5 Strip portion 6 Flat blade

Claims (5)

[Claims] 1. A stirring type polymerization machine equipped with, as stirring blades, a stirring blade having a lattice blade having a bottom paddle on the stirring shaft or a plurality of flat blade blades positioned vertically and intersecting with each other in a plane direction within a range in which stirring can be performed by the stirring blades. 1. A method for producing monodisperse polymer beads, which comprises producing a monodisperse polymer bead by filling an aqueous dispersion medium and supplying droplets of a polymerizable liquid formed through an orifice plate to polymerize while stirring. 2. The method of claim 1 wherein the orifice plate is disposed in the stirred polymerization machine, at the bottom. 3. The method of claim 1, wherein the orifice plate is disposed in a droplet generator having an outlet capable of supplying droplets of the polymerizable liquid to the stirred polymerization machine. 4. The period of vibration is generated by droplets of the polymerizable liquid passing through the orifice plate to form a liquid column of the polymerizable liquid having a laminar flow property and vibrating the liquid column. The method of claim 1 formed as a group of synchronized drops. 5. The method according to claim 1, wherein the stirring is performed at a blade tip speed of 0.1 to 2.0 m / s.