WO2016121596A1 - Method for improving dispersibility of aqueous emulsion and method for manufacturing aqueous emulsion having improved dispersibility - Google Patents

Abstract

The present invention addresses the problem of providing a method that is capable of efficiently separating and refining an aggregated body in an aqueous emulsion and that is capable of a high-throughput at low costs. This problem is addressed with a method for improving dispersibility of an aqueous emulsion that depressurizes a stir/mix tank 10 in which the aqueous emulsion E is placed to a pressure at which dissolved air included in the aqueous emulsion is removed, and that collides the aqueous emulsion together after the depressurizing treatment. The method for improving dispersion of an aqueous emulsion is characterized in that the aqueous emulsion E is circulated by continuously collecting, in a liquid pressurization mechanism 20, a portion of the liquid inside the tank E1 which is the aqueous emulsion inside the stir/mix tank 10 and by spraying, toward the inside of the stir/mix tank 10, a pressurized liquid E3 which is the aqueous emulsion pressurized by the liquid pressurization mechanism 20 and when spraying the pressurized liquid E3 toward the inside of the stir/mix tank 10, the pressurized liquid E3 is collided with the liquid inside the tank E1 to improve the dispersibility of microparticles in the aqueous emulsion.

Description

Method for improving dispersibility of aqueous emulsion and method for producing aqueous emulsion with improved dispersibility

The present invention relates to a method for improving the dispersibility of an aqueous emulsion, and more particularly, to separate agglomerates of fine particles formed by agglomeration of fine particles in an aqueous emulsion into individual fine particles by efficient physical treatment. This relates to a method for improving the dispersibility of an aqueous emulsion carried out by the above method.
Moreover, this invention relates to the water-based emulsion which improved the dispersibility by this method, and the water-based coating material containing the same.

An aqueous emulsion, which is an emulsion in which resin fine particles are dispersed in water, is widely used for applications such as paints, adhesives, inks, and surface treatment agents.
Water-based paints using water-based emulsions are used for various applications such as rust prevention, antifouling, mold prevention, insulation, heat insulation or snow prevention.
Water-based paints that use water-based emulsions form a coating film with the resin as the main component after the water evaporates, but when the coating film is formed, the coating properties and adhesion Insulation properties are a problem.

Usually, the resin fine particles in the aqueous emulsion are present not only in the form of single resin fine particles but also in the form of aggregates of various sizes in which a plurality of resin fine particles are aggregated.
The agglomerates are important properties as a paint and cause a decrease in coating properties, adhesion, and the like. Therefore, in an aqueous emulsion used as a paint, the agglomerates are divided into individual fine particles or a larger size. It is desirable to separate even small agglomerates, that is, to make the dispersibility of the aqueous emulsion good.

Patent Document 1 reports a dispersion method of a mixture in which a dispersoid such as an aqueous emulsion and a solvent are mixed using a supercritical fluid such as carbon dioxide.

In Patent Document 2, a high speed is imparted by pressurizing an aqueous mixture obtained by low-pressure stirring, and the aqueous mixture imparted with a high speed is jetted and collided so as to face each other. A method for dispersing agglomerates of resin fine particles has been reported. In the apparatus used in the method of Patent Document 2, the step of stirring the aqueous mixed solution in a reduced pressure state and the step of jetting and colliding the pressurized aqueous mixed liquids are performed in separate reactors. It is completely separated.

However, the method described in Patent Document 1 requires a large-scale apparatus in the method of bringing the entire liquid in the reactor into a supercritical state, and the method described in Patent Document 1 is not practical from the viewpoint of cost.

In addition, the ease of formation and separation of agglomerates and the degree of aggregation depend on the type of resin fine particles, the type of additives such as polymerization initiators and surfactants, and the processing conditions during stirring, pressurization, and injection. For this reason, there is a case where the separation of the agglomerates is insufficient in one treatment. The method described in Patent Document 2 is a batch type, and in order to sufficiently separate the agglomerates, the treated liquid that has been processed may be put into the apparatus again, and it may be necessary to repeat the processing several times. It took time and effort to input and remove raw materials, and there were limits in terms of cost and processing capacity.

Water-based paints are widespread in a wide range of technical fields, and in addition to the desire for water-based emulsions that achieve higher levels of dispersion, agglomerates in the water-based emulsions can be efficiently produced at low cost. Therefore, it has been desired to develop a method that can be separated into a large amount and capable of mass processing.

Japanese Patent Laid-Open No. 10-192670 Japanese Patent No. 4568792

The present invention has been made in view of the above-described background art, and its object is to provide a method capable of efficiently separating and refining agglomerates in an aqueous emulsion and capable of mass processing at low cost. In addition, another object is to provide an aqueous emulsion in which agglomerates are sufficiently separated and refined and is excellent when used as a paint or the like.

As a result of intensive studies to solve the above-mentioned problems, the present inventor, as described in Patent Document 2, separately pressurized liquids obtained by pressurizing the liquid in the tank subjected to the depressurization treatment, Even if it does not collide in a special device that exists independently, `` pressurized liquid obtained by pressurizing the liquid in the tank that has been decompressed '' can be collided with the liquid in the tank in the stirring and mixing tank. For example, it has been surprisingly found that the agglomerates can be sufficiently separated and dispersed into individual fine particles or even smaller fine particles.
Further, it was found that the agglomerates can be separated more suitably by colliding the pressurized liquid with the liquid in the tank in a reduced pressure state (for example, atmospheric pressure (1 atm) is not applied).

As a result, a part of the aqueous emulsion in the stirring and mixing tank in a reduced pressure state is continuously collected and pressurized, and sprayed into the stirring and mixing tank to cause collision between the aqueous emulsions, thereby agglomerating. The mass can be separated.

Furthermore, the present inventor, in such a method, once collected aqueous emulsion returns to the original stirring and mixing tank (the aqueous emulsion circulates), so that a high level of dispersion is caused by repeated collisions. It becomes possible, and continuous processing is possible without repeated charging and removal of raw materials, enabling mass processing, and finding that it can efficiently separate agglomerates and improve dispersibility, The present invention has been completed.

That is, the present invention reduces the pressure in the stirring and mixing tank into which the aqueous emulsion is charged to a pressure at which dissolved air contained in the aqueous emulsion is removed, and dispersibility of the aqueous emulsion that causes the aqueous emulsions after the decompression treatment to collide with each other An improved method,
A part of the liquid in the tank, which is an aqueous emulsion present in the stirring and mixing tank, is continuously collected in the liquid pressurizing mechanism, and the pressurized liquid that is the aqueous emulsion pressurized by the liquid pressurizing mechanism is stirred. A water-based emulsion is circulated by spraying into the mixing tank,
Dispersibility of an aqueous emulsion characterized by improving the dispersibility of fine particles in the aqueous emulsion by colliding with the liquid in the tank when the pressurized liquid is jetted into the stirring and mixing tank An improved method is provided.

The present invention also provides a method for producing an aqueous emulsion, characterized by using the above-described method for improving the dispersibility of an aqueous emulsion.

The present invention also provides an apparatus for improving the dispersibility of an aqueous emulsion, characterized by being used for the above-described method for improving the dispersibility of an aqueous emulsion.

The present invention also provides an aqueous emulsion characterized in that the dispersibility is improved by the above-described method for improving the dispersibility of an aqueous emulsion.

The present invention also provides an aqueous paint characterized by containing the above aqueous emulsion.

According to the present invention, agglomerates of fine particles in an aqueous emulsion can be sufficiently separated and refined, and the dispersibility of the aqueous emulsion can be improved to a higher level.
That is, by reducing the pressure in the stirring and mixing tank into which the aqueous emulsion is charged and removing the “dissolved air containing dissolved oxygen” in the aqueous emulsion, the separation of agglomerates due to the collision between the aqueous emulsions can be promoted. As a result, the dispersibility of the aqueous emulsion can be improved to a level higher than conventional levels.
Moreover, since the atmospheric pressure is not applied to the aqueous emulsion in the stirring and mixing tank, it can be dispersed well and can be maintained even after the good dispersion state is returned to normal pressure.

Therefore, the aqueous emulsion whose dispersibility has been improved by the method of the present invention is used for rust prevention, antifouling, antifungal, insulation, heat insulation, adhesion when used in applications such as paints, adhesives, inks, and surface treatment agents. It shows excellent properties that are not available in the past for various performances such as snow prevention.

Specifically, for example, when an aqueous emulsion whose dispersibility is improved by the method of the present invention is used as an aqueous paint, the fine particles are uniformly distributed on the surface of the substrate as compared with the case where a conventional aqueous emulsion is used. It becomes easy to align.
As a result, deterioration due to ultraviolet rays, contact with rainwater, and generation of rust due to high humidity are reduced, so that the water-based paint obtained by the method of the present invention has high weather resistance.
In addition, since the fine particles in the aqueous emulsion can be uniformly aligned on the surface of the base material to form a coating film, the use of the aqueous coating material obtained by the method of the present invention can provide insulation resistance, heat resistance, flame resistance, etc. An excellent, strong and strong coating film can be obtained.
Furthermore, if the aqueous emulsion obtained by the method of the present invention is prepared in a state where impurities are removed, the above performance is further improved.

In the method of the present invention, a pressurized aqueous solution is collided with an aqueous emulsion from which "dissolved air containing dissolved oxygen" is removed under reduced pressure, and agglomerates of fine particles are separated and finely divided by the energy of the collision. As in the method using a supercritical fluid, the same effect is obtained without requiring a large-scale apparatus, and the cost, safety and productivity are excellent.

The method of the present invention is a method in which a part of the aqueous emulsion is collected from the stirred and mixed tank in a reduced pressure state, pressurized, and sprayed toward the original stirred and mixed tank. Circulates, the number of collisions can be increased and continuous processing is possible.
Therefore, as in the batch method of Patent Document 2, if the number of collisions is to be increased, the raw material must be repeatedly charged and taken out many times, and the agglomerates can be efficiently separated and refined. It can proceed and productivity is greatly improved. For example, compared with the batch method described in Patent Document 2, the method of the present invention increases the production capacity by 2 times or more (6 times or more depending on the type of water-based emulsion, type of apparatus, injection pressure, processing time, etc.). It is possible. In addition, there is no separate special collision device, so it is difficult to use the device for nuclear weapon development.

In the case of an aqueous emulsion containing individual fine particles or small-sized aggregates, re-aggregation of the fine particles may occur during or after the dispersion treatment. In the method of the present invention, it is possible to suppress re-aggregation of fine particles by performing charging treatment on the aqueous emulsion, particularly preferably by performing charging treatment in the middle of circulating in the apparatus, and excellent dispersibility. In addition to being obtained, the dispersed state of the fine particles can be well maintained over a long period of time.
Further, when water evaporates after being applied to the substrate, fine particles having the same charge are easily aligned on the substrate in the emulsion.

It is a schematic diagram which shows the outline of an example (embodiment in which a pressurized liquid injection part exists in the side surface of a stirring and mixing tank) used for the dispersibility improvement method of the aqueous emulsion of this invention. An example of an apparatus used in the method for improving the dispersibility of an aqueous emulsion of the present invention (embodiment in which a pressurized liquid injection part is present in a hollow part of a stirring and mixing tank and the pressurized liquids injected from two directions collide with each other) It is a schematic diagram which shows an outline. It is a schematic diagram which shows the outline of an example (piston) of a liquid pressurization mechanism. It is a schematic diagram which shows the outline of an example (embodiment which charges a collection liquid using a charging mechanism) used for the dispersibility improvement method of the aqueous | water-based emulsion of this invention. It is an explanatory view showing the state of fine particles in an aqueous emulsion and an aqueous paint. (A) Conventional water-based emulsion or water-based paint in which agglomerates of fine particles are present (b) Water-based emulsion or water-based paint improved in dispersibility (separated and refined) by the method of the present invention It is a graph which shows the particle size distribution of the microparticles | fine-particles of the acrylic emulsion before and behind performing the process by the dispersibility improvement method of the aqueous emulsion of this invention. (A) Conventional particle size distribution before treatment by the method of the present invention (b) Particle size distribution after treatment by the method of the present invention It is a cross-sectional schematic diagram of the stirring mixing tank which shows an example of the injection method of a pressurized liquid.

Hereinafter, the present invention will be described, but the present invention is not limited to the following embodiments, and can be implemented with arbitrary modifications.

<Overview of overall device configuration>
The method for improving the dispersibility of the aqueous emulsion of the present invention will be described while showing the constitution of the apparatus. Examples of “an apparatus for improving the dispersibility of an aqueous emulsion” used in the method for improving the dispersibility of an aqueous emulsion of the present invention are shown in FIGS.

The aqueous emulsion dispersibility improving apparatus of the present invention (hereinafter sometimes simply referred to as “dispersibility improving apparatus”) includes a stirring / mixing tank 10 to which a decompression mechanism 30 is connected, a liquid pressurizing mechanism 20 and a pressurizing mechanism 20. A pressure fluid injection unit 14 is provided.
The aqueous emulsion E, which is the object to be treated, circulates through the stirring / mixing tank 10 and the liquid pressurizing mechanism 20 via the pressurized liquid ejecting section 14, and aggregates in the aqueous emulsion are separated into individual fine particles or small size. The process of separating into agglomerates (hereinafter sometimes simply referred to as “process”) is performed continuously.

The stirring / mixing tank 10 has a stirring mechanism 11 so that the liquid charged therein can be stirred, and the aqueous emulsion E is charged into the stirring / mixing tank 10.

The stirring / mixing tank 10 is connected to a decompression mechanism 30, and the inside of the stirring / mixing tank 10 is decompressed by the decompression mechanism 30 during processing. During processing, the pressure in the stirring and mixing vessel 10 is reduced to a pressure at which dissolved air contained in the aqueous emulsion is removed.
By reducing the pressure in the stirring and mixing tank 10, the force acting between the fine particles in the aqueous emulsion becomes weak, and water, a surfactant, etc. enter between the fine particles, and the binding force between the fine particles becomes weak. Is difficult to form agglomerates, and the agglomerates are easily separated and refined.
In addition, dissolved air (oxygen) is dissolved in the aqueous emulsion before treatment, which hinders separation and refinement of fine particles. By depressurizing the inside of the stirring and mixing tank 10, such dissolved air (oxygen) can be removed, and the fine particles can be easily separated and refined. That is, when the dissolved air (oxygen) is removed, the energy of collision between the aqueous emulsions directly (effectively) acts to separate and refine the fine particles.

A part of the aqueous emulsion that has undergone the pressure reduction treatment is collected from the stirring and mixing tank 10, enters the liquid pressurizing mechanism 20, and is jetted toward the stirring and mixing tank 10 while being pressurized there. That is, in the present invention, the aqueous emulsions after the pressure reduction treatment collide with each other in the stirring and mixing tank 10.
In this way, by colliding the aqueous emulsions after the decompression treatment, the fine particles whose binding force has been weakened by the decompression treatment are suitably separated and refined by the energy of the impact (aggregates are separated and refined). Further, the dissolved air (oxygen) that hinders dispersion is removed by reducing the pressure, and the dispersibility of the fine particles in the aqueous emulsion is improved.

In the present invention, the pressure reduction in the stirring and mixing tank 10, the collection of the aqueous emulsion into the liquid pressurizing mechanism 20, and the injection collision of the pressurized aqueous emulsion are continuously performed in the dispersibility improving apparatus 1, that is, aqueous While the emulsion E is circulated inside the dispersibility improving apparatus 1, the agglomerates are separated.
In the present invention, among aqueous emulsions E, those present in the stirring and mixing tank 10 are “liquid in the tank (E1)”, and those once taken out of the stirring and mixing tank 10 are referred to as “collected liquid (E2)”. “A pressurized liquid (E3)” is a state in which the agglomerates are pressurized to a pressure sufficient to suitably separate and refine the agglomerates by collision.

Valves (open / close valves) are appropriately provided in the piping between the stirring and mixing tank 10 and the pressure reducing mechanism 30 and between the stirring and mixing tank 10 and the liquid pressurizing mechanism 20, and in principle, these valves are connected during processing. When opened, continuous processing is performed, and these valves are closed when the raw material is charged or when the material is taken out after the processing is completed.

<Stirring and mixing tank 10>
The aqueous emulsion E is put into the stirring and mixing tank 10 at the start of operation. Although the charging portion of the aqueous emulsion E is not shown, the position and shape thereof are not particularly limited, and the position is preferably present in the upper portion of the stirring and mixing tank 10 for ease of charging (see FIG. Not shown).

The stirring / mixing tank 10 may be stirred by spraying the pressurized liquid E3 into the stirring / mixing tank as described later (for example, as shown in FIG. 7). It is preferable to have the mechanism 11. There is no limitation in particular about the kind of stirring mechanism 11, and what can stir the inside of the tank of the stirring mixing tank 10 uniformly can be selected suitably. In the drawing, a form having a stirring blade in the central axis portion is illustrated, but for example, a stirring mechanism 11 having a stirring blade outside the central axis (near the inner wall of the stirring and mixing tank 10) may be used. A stirring mechanism 11 having both (double) stirring blades is also preferred.
There are no particular limitations on the operating conditions (such as the number of revolutions) of the stirring mechanism 11, and conditions that allow uniform stirring in the tank are selected as appropriate. When the stirring mechanism 11 is provided, not only can the composition and temperature of the liquid E1 in the tank be made uniform, but excessive liquid level rise due to bumping of the liquid E1 in the tank and generation of bubbles during the decompression process can be avoided.

Volume of the stirring mixing tank 10 is not particularly limited, 300L (liter) or more 5 m ³ or less, more 2m ³ and particularly preferably 500L.
When the volume is not less than the above lower limit, a sufficient throughput can be achieved, and mass production and cost reduction, which are the effects of the present invention, can be achieved more (synergistically). Further, when the amount is not more than the above upper limit, the apparatus is not too large and advantageous in terms of cost, the workability is good, and the inside of the tank is easily stirred sufficiently uniformly.

During the treatment, the filling rate of the liquid E1 in the tank inside the stirring and mixing tank 10 (value obtained by dividing the volume of the liquid E1 in the tank existing in the stirring and mixing tank 10 by the volume of the stirring and mixing tank 10) is usually It is 20% or more and 90% or less, and preferably 40% or more and 80% or less.
When the filling rate is within the above range, the inside of the agitation and mixing tank 10 can be easily and stably decompressed, and the inside of the tank can be uniformly stirred with little scattering of the liquid E1 in the tank. Will improve. Although the volume of the liquid E1 in the tank may decrease due to the reduced pressure, it is preferable to maintain the above range even in that case.

The stirring and mixing tank 10 is connected to the decompression mechanism 30 in the exhaust part 12. The position of the exhaust part 12 is not particularly limited as long as it is above the liquid level of the in-tank liquid E1. There is no particular limitation on the shape, size, etc. of the exhaust part 12, and it is an appropriate pressure to be described later in the tank, that is, a pressure equal to or higher than the saturated vapor pressure of water that is a dispersion medium of the aqueous emulsion (liquid E1 in the tank). And what is necessary is just to be able to hold | maintain stably at the pressure which can fully remove the dissolved air in aqueous | water-based emulsion (liquid E1 in a tank).

A preferable pressure in the stirring and mixing tank 10 is a pressure at which dissolved air or the like can be removed and the amount of the (circulating) aqueous emulsion E is less likely to decrease, that is, a level equivalent to or slightly higher than the saturated vapor pressure of water (for example, saturated vapor of water The pressure is about 1 to 1.5 times the pressure. When the temperature of the liquid E1 in the tank is in the range described later, the inside of the stirring and mixing tank 10 may be reduced to a pressure slightly higher than the vapor pressure of water at that temperature.

When the pressure in the stirring and mixing tank 10 becomes lower than the saturated vapor pressure of water due to the reduced pressure, the aqueous emulsion E boils and the aqueous emulsion E is circulated between the stirring and mixing tank 10 and the liquid pressurizing mechanism 20. Therefore, the pressure in the stirring and mixing tank 10 is preferably equal to or higher than the saturated vapor pressure at the temperature of the aqueous emulsion (liquid E1 in the tank).

The vapor pressure of water is shown below.
Water temperature (℃) Vapor pressure (kPa)
0 0.611
4 0.841
5 0.873
10 1.23
20 2.33
30 4.24
40 7.37
50 12.3
60 19.9
70 31.2
80 47.5
100 101.3

The inside of the stirring and mixing tank 10 is exhausted by the pressure reducing mechanism 30, and even if water in the aqueous emulsion (liquid E1 in the tank) evaporates to some extent, a “preferable pressure (decompression degree) that maintains the effect of the present invention, Set pressure reduction time, temperature, etc.
Here, “preferred” means that when water evaporates, the particle concentration and viscosity of the aqueous emulsion increase. Even at the increased fine particle concentration and viscosity, the pressurized liquid E3 is injected into the in-tank liquid E1. That is, there is no problem in separating and refining the agglomerates by colliding with each other, and the amount of the liquid E1 in the tank is reduced so that the circulation of the aqueous emulsion E is not hindered.

The temperature of the bath liquid E1 in the stirring and mixing bath 10 during operation is not particularly limited, but is preferably 0 ° C. or higher and 60 ° C. or lower, more preferably 1 ° C. or higher and 40 ° C. or lower, and particularly preferably 2 ° C. or higher and 30 ° C. or lower. It is preferably 4 ° C. or higher and 20 ° C. or lower.
However, first, after depressurizing the inside of the stirring and mixing tank 10 to remove dissolved air, as a next stage, when the pressurized liquid E3 is injected into the stirring and mixing tank 10 to perform circulation operation, the previous stage (injection It is also preferable that the temperature of the liquid E1 in the tank in the dissolved air removal stage before circulation is higher by 0 ° C. or more and 20 ° C. or less than the above upper and lower limit temperatures.
The apparatus used for temperature adjustment is not particularly limited, but a known apparatus such as a cooler provided mainly in contact with the outside of the stirring and mixing tank 10 such as a jacket type or a cooling pipe type may be used.

When the upper limit of the temperature of the liquid E1 in the tank is not more than the above, the pressure for preventing the liquid E1 in the tank from boiling (that is, the saturated vapor pressure of the aqueous emulsion) can be kept low, so Since no pressure (external pressure) is applied from the surroundings, the separation and refinement of the agglomerates proceeds suitably. Further, the evaporation of water is suppressed, the amount of the liquid E in the tank is kept constant, and the rate of increase in the particle concentration and viscosity of the aqueous emulsion (tank liquid E1) is suppressed.
On the other hand, when the lower limit of the temperature of the liquid E1 in the tank is not less than the above, there is no possibility that the temperature further decreases due to the heat of evaporation to become solid (ice), and dissolved air (dissolved oxygen) is easily removed.

The decompression time is not particularly limited as long as the dissolved air contained in the aqueous emulsion is sufficiently removed, and the volume of the stirring and mixing tank 10, the amount of exhaust, the method of adjusting the exhaust speed, the degree of decompression, etc. 2 minutes to 60 minutes, preferably 5 minutes to 40 minutes, more preferably 10 minutes to 20 minutes, in particular, from the start of decompression (exhaust) to the circulation and injection of the aqueous emulsion. preferable.
The pressure reduction may be started and the injection / circulation may be started preferably after the above time has elapsed, but the pressure reduction and the injection / circulation may be started simultaneously.

As described above, it is preferable that the pressure in the stirring and mixing tank 10 is equal to or higher than the saturated vapor pressure at the temperature of the liquid E1 in the tank in order to prevent boiling, but “(described above) water at the temperature of the liquid E1 in the tank. Is 1 to 4 times, more preferably 1 to 2 times, particularly preferably 1 to 1.5 times, and more preferably 1.1 to 1.5 times. Two times or less is more preferable.
That is, for example, when the temperature of the liquid E1 in the tank is 4 ° C., 0.8 kPa (6 Torr) or more and 3.4 kPa or less is preferable, and 0.8 kPa or more and 1.2 kPa or less is particularly preferable. For example, when the temperature of the in-bath liquid E1 is 20 ° C., it is preferably 2.3 kPa (18 Torr) or more and 9.3 kPa or less, and particularly preferably 2.3 kPa or more and 3.5 kPa or less.

The stirring / mixing tank 10 preferably includes means for measuring pressure and temperature (not shown), and preferably includes means for uniformly controlling the temperature in the stirring / mixing tank 10 (FIG. Not shown). Furthermore, it is preferable that the position and state (whether it is not boiling) of the liquid E1 in the tank E1 in the stirring and mixing tank 10 can be visually monitored.

During the treatment, it is necessary to measure the pressure and temperature in the stirring and mixing tank 10 and adjust the exhaust speed by the decompression mechanism 30 to adjust the inside of the stirring and mixing tank 10 to an appropriate pressure. Care must be taken so that the liquid E1 in the tank does not boil.

When pressure reduction in the stirring and mixing tank 10 is started, the liquid level of the liquid E1 in the tank rises once, the air dissolved in the liquid E1 in the tank expands to generate bubbles, and the air is removed from the exhaust part 12 together with water vapor. Is done.
In this state, if the inside of the stirring and mixing tank 10 is still evacuated, the liquid level of the liquid E1 in the tank drops and becomes stationary for a certain time, and thereafter the liquid E1 in the tank starts to boil. At that time, the operator checks the position of the liquid level, and immediately before starting boiling or immediately after starting boiling, the pressure can be adjusted by closing the valve between the exhaust unit 12 and the pressure reducing mechanism 30. preferable.
However, even if the amount of the aqueous emulsion E is slightly reduced, such a case is not outside the scope of the present invention as long as it does not interfere with the effects of the present invention.

Moreover, the stirring and mixing tank 10 has an in-tank liquid collection part 13 for collecting the in-tank liquid E1. A part of the liquid E1 in the tank, which is the aqueous emulsion E present in the stirring and mixing tank 10, is continuously collected in the liquid pressurizing mechanism 20 and pressurized there.

The position of the liquid collection unit 13 in the tank is not particularly limited as long as it is always below the liquid level of the liquid E1 in the tank, but the liquid level of the liquid E1 in the tank may drop due to the decompression process. However, the tank liquid collection part 13 needs to be below the liquid level of the tank liquid E1.
As shown in FIG. 1, only one in-vessel liquid collection unit 13 may exist in the stirring and mixing vessel 10, or a plurality of in-vessel liquid collection units 13 may exist as shown in FIGS. 2 and 4.
Moreover, as shown in FIG.2 and FIG.4, the some liquid collection part 13 in a tank may exist in the different height in the stirring mixing tank 10, and in such a case, the quantity of the liquid E1 in a tank, etc. Depending on the conditions, the in-bath liquid collection unit 13 used for collection can be changed by opening and closing a valve or the like.

The stirring and mixing tank 10 has a pressurized liquid ejecting unit 14 for ejecting the pressurized liquid E3 pressurized by the liquid pressurizing mechanism 20.
The pressurized liquid E3 that is the aqueous emulsion E pressurized by the liquid pressurizing mechanism 20 is ejected from the pressurized liquid ejecting unit 14 into the stirring and mixing tank 10. At the same time, the aqueous emulsion E is returned to the stirring and mixing vessel 10 so that the aqueous emulsion E circulates in the apparatus.

In the present invention, when the pressurized liquid E3 is sprayed into the stirring and mixing vessel 10, the dispersibility of the fine particles in the aqueous emulsion is improved by causing the pressurized solution E3 to collide with the in-vessel solution E1, that is, Separation and refinement of fine particle agglomerates into finer ones.
Since the pressurized liquid E3 is sprayed toward the stirring and mixing tank 10 and the pressurized liquid E3 collides with the liquid E1 in the tank at a high speed, the separation and refinement of the agglomerates proceeds. The nozzle shape is preferable.
The inner diameter of the nozzle tip is not particularly limited, but is preferably 0.03 mm or more and 0.3 mm or less, and 0.05 mm or more in order to obtain a “speed of pressurized liquid” sufficient for separation and refinement of agglomerates. 0.15 mm or less is particularly preferable.

The position of the pressurized liquid injection unit 14 is not particularly limited as long as it is below the liquid level of the in-tank liquid E1 (if the injected pressurized liquid E3 can collide with the in-tank liquid E1). As shown in FIG. 1, when the pressurized liquid injection unit 14 is provided on the side surface of the stirring and mixing tank 10, the vertical position of the pressurized liquid injection unit 14 is upward from the vertical position of the stirring blades of the stirring mechanism 11. Alternatively, it is preferable to shift it downward because the impact of injection is less likely to be applied to the stirring blade. When there are two (or more) agitating blades as shown in FIG. 1, the vertical position of the pressurized liquid ejecting section 14 is provided substantially at the center of the two agitating blades as shown in FIG. It is particularly preferable because it is not given.

Further, the number of the pressurized liquid ejecting units 14 is not particularly limited. As illustrated in FIGS. 1 and 4, one pressurized liquid ejecting unit 14 may exist in the stirring and mixing tank 10. As shown in FIG. 2, two pressurized liquid ejecting units 14 may exist in the stirring and mixing tank 10, or three or more pressurized liquid ejecting units 14 may exist.

FIG. 1 shows an example of a relatively simple embodiment of the present invention. One in-vessel liquid collecting section 13 and one pressurized liquid are provided on the wall surface of a substantially cylindrical stirring and mixing tank 10. The injection part 14 exists.
The in-tank liquid E1 is collected in the liquid pressurizing mechanism 20 from the in-tank liquid collecting unit 13, and the pressurized liquid E3 pressurized by the liquid pressurizing mechanism 20 is ejected from the pressurized liquid ejecting unit 14. As a result, the mixture returns to the agitation / mixing tank 10 and collides with the in-vessel liquid E1 in the agitation / mixing tank 10, whereby separation and refinement of the agglomerates of fine particles proceed.

2 and 4 show another example of the embodiment of the present invention, which is a more preferable embodiment. That is, the stirring and mixing tank 10 has a hollow portion 15, and the pressurized liquid E <b> 3 is injected into the hollow portion 15.
Although the hollow part 15 may exist in the lower part and side surface of the stirring and mixing tank 10, it is preferable to exist in the lower part of the stirring and mixing tank 10 as shown in FIG.2 and FIG.4.

When the stirring / mixing tank 10 has the recessed portion 15, as shown in FIG. 4, the pressurized liquid E <b> 3 may be injected from one direction into the recessed portion 15 (the pressurized liquid injection unit 14 is 1). However, as shown in FIG. 2, it is possible to inject the pressurized liquid E3 from at least two directions into the recessed portion 15 and cause the pressurized liquids E3 injected from different directions to collide with each other. It is preferable for separation and refinement of the lump.
The number of directions in which the pressurized liquid E3 is ejected (number of the pressurized liquid ejecting units 14) is one direction (one), two directions (two), three directions (three), or four directions (four). Preferably, one direction (one) or two directions (two) is more preferable, and two directions (two) are particularly preferable. If there are too many directions to spray, the apparatus becomes complicated, leading only to an increase in cost, and the efficiency of processing is not improved.

When there are a plurality of the pressurized liquid ejecting units 14, as shown in FIG. 2, the aggregates of the aggregates can be separated more efficiently by causing the pressurized liquids E <b> 3 ejected from the pressurized liquid ejecting units 14 to collide with each other. Can proceed. When the stirring / mixing tank 10 has the recessed portion 15, the distance between the pressurized liquid ejecting portions 14 can be shortened by providing the pressurized liquid ejecting portion 14 in the recessed portion 15. Demonstrate.
When two pressurized liquid ejecting units 14 are installed in the recessed portion 15 as shown in FIG. 2, the distance between the pressurized liquid ejecting units 14 (the distance between the tips of the two nozzles) is preferably It is 1 mm or more and 100 mm or less, and particularly preferably 2 mm or more and 50 mm or less. When the pressurized liquids E3 collide with each other, if the distance between the pressurized liquid ejecting portions 14 from which the pressurized liquids E3 are ejected is short (less than the above upper limit), the pressurized liquid E3 is applied with a large velocity energy. The pressure fluids E3 can collide with each other, and the efficiency of separation and refinement of the agglomerates is improved.

Further, when the pressurized liquid E3 is sprayed from the side surface of the stirring and mixing tank 10 as shown in FIG. 1, it is added while being shifted in the horizontal direction from the direction of the rotation axis of the stirring mechanism 11, that is, the central axis direction of the stirring and mixing tank 10. It is preferable to inject the pressure fluid E3. When sprayed in the direction of the central axis of the stirring and mixing tank 10, an impact may be applied to the rotating shaft of the stirring mechanism 11.
In particular, spraying in such a direction from two (or more) side surfaces of the stirring / mixing tank 10 is preferable because it is easy to achieve the target.
In FIG. 7, the injection direction of the pressurized liquid E3 is indicated by an arrow in the schematic cross-sectional view of the stirring and mixing vessel 10. The angle shifted from the central axis direction to the horizontal direction, that is, the angle α shown in FIG. 7 is not particularly limited as long as the above effect is obtained, but α is preferably 20 ° or more and 80 ° or less, and 35 ° or more and 75 ° or less. Is more preferable, and 50 ° to 70 ° is particularly preferable.
If the angle α is in this range, it is possible to stir the liquid E1 in the tank without giving an impact to the rotating shaft of the stirring mechanism 11, and when the pressurized liquid injection unit 14 is installed in the stirring and mixing tank 10. Processing such as drilling of the stirring and mixing tank 10 is easy.

As shown in FIG. 1, when the pressurized liquid E3 is sprayed from the side surface of the stirring and mixing tank 10, the spraying direction is preferably a substantially horizontal direction or obliquely downward with respect to a horizontal plane.
The angle in the horizontal direction or obliquely downward (the angle between the horizontal plane and the injection direction) is not particularly limited, but is preferably 0 ° or more and 60 ° or less, more preferably 5 ° or more and 45 ° or less, and more preferably 10 ° or more and 30 ° or less. Is particularly preferred. When sprayed upward, the pressurized liquid E3 may be ejected from the surface of the liquid E1 in the tank.

As shown in FIG. 4, when the pressurized liquid E3 is sprayed from one direction to the hollow portion 15 of the stirring and mixing tank 10, the spraying direction is a substantially horizontal direction or is obliquely upward with respect to the horizontal plane. Preferably there is.
The angle in the horizontal direction or obliquely downward (the angle between the horizontal plane and the injection direction) is not particularly limited, but is preferably 0 ° or more and 60 ° or less, more preferably 5 ° or more and 45 ° or less, and more preferably 10 ° or more and 30 ° or less. Is particularly preferred. When jetted downward, the liquid flow may hit the bottom of the recessed portion 15 or the ejection port 16 may be impacted.

As shown in FIG. 2, even when the pressurized liquid E3 ejected from two different directions in the hollow portion 15 is caused to collide, is the injection direction of the pressurized liquid E3 in the hollow portion 15 substantially horizontal? Alternatively, it is preferably obliquely upward with respect to the horizontal plane. On the other hand, when the pressurized liquid is ejected in the substantially horizontal direction at the same height from the two directions (that is, when the angle is 0 °), the pressurized liquid The collision efficiency between E3 becomes high and is preferable.

Further, when a collision plate (preferably a collision plate curved convexly downward) (not shown) is provided at the bottom of the stirring mechanism 11, the stirring mechanism 11 is not easily damaged by the jet, and the pressurized liquid E3 It is particularly preferable that the jetting direction is obliquely upward with respect to the horizontal plane, since the pressurized liquid E3 collides with the collision plate, and the separation / miniaturization of the agglomerates is promoted.

After completion of the treatment, the take-out port 16 for taking out the aqueous emulsion E in the stirring / mixing tank 10 may be present anywhere in the stirring / mixing tank 10, but is present in the lower part of the stirring / mixing tank 10 for easy removal. It is preferable.

<Decompression mechanism 30>
There is no limitation in particular in the kind of pressure reduction mechanism 30, What is necessary is just to be able to depressurize the inside of the stirring mixing tank 10 to the above-mentioned appropriate pressure, and a well-known vacuum pump etc. can be used. It is preferable to provide a mechanism (not shown) for trapping water or the like before the decompression mechanism 30 (between the decompression mechanism 30 and the stirring and mixing tank 10).

In the present invention, the pressure reduction in the stirring and mixing vessel 10 is performed in order to remove the dissolved air contained in the aqueous emulsion and to reduce the external pressure applied around the agglomerates at the time of collision. The degree of pressure (pressure in the stirring and mixing tank 10), the pressure reduction time, etc. are as described above.

<Liquid pressure mechanism 20>
The liquid pressurizing mechanism 20 pressurizes the collected liquid E2 collected from the in-tank liquid collecting unit 13, and “provides the kinetic energy necessary to promote the separation and refinement of the fine particles when colliding with the in-tank liquid E1. The pressurized pressurized liquid E3 is jetted from the pressurized liquid jetting unit 14 of the stirred and mixed tank 10 into the stirred and mixed tank 10.

The liquid pressurizing mechanism 20 may be anything as long as it can pressurize the collected liquid E2, but as an example, the structure of the pressurizing chamber as shown in FIG. Is mentioned.
In the case shown in FIG. 3, the sample liquid E2 is pressurized in the cylinder 21 by pressing the piston, and is ejected from the pressurized liquid ejecting section 14 having a nozzle shape or the like as the pressurized liquid E3.

The pressure of the pressurized liquid E3 when ejected from the pressurized liquid ejecting section 14 is preferably 3 MPa (30 atm) or more and 250 MPa (2500 atm) or less, although it depends on the type of aqueous emulsion to be treated. 100 MPa) to 50 MPa (500 atmospheres) is more preferable, and 20 MPa (200 atmospheres) to 25 MPa (250 atmospheres) is particularly preferable.
If the pressure of the pressurized liquid E3 is within the above range, the kinetic energy at the time of collision is sufficient, so the efficiency of separation and refinement of the agglomerates is good. In addition, the stirring / mixing tank 10, the pressurized liquid injection unit 14, etc. Since an excessive load is not applied, it is difficult for the apparatus to fail.
Moreover, it is preferable that the pressure of the pressurized liquid is set to a relatively small pressure immediately after the start of circulation (injection), and is gradually increased to a steady state.

The speed of the pressurized liquid E3 immediately after being ejected from the pressurized liquid ejecting section 14 is not particularly limited, but is preferably 50 m / s or more and 1500 m / s or less, more preferably 200 m / s or more and 500 m / s or less, and 100 m. / S to 800 m / s is particularly preferable.
If the speed immediately after jetting is in the above range, the kinetic energy is sufficient, so the efficiency of separation and refinement of the agglomerates is good. On the other hand, the stirring / mixing tank 10 and the pressurized liquid jetting unit 14 are excessively large. Hard to load.
When a collision occurs under the above-mentioned conditions, the location of the collision becomes locally high, but the liquid E1 in the tank is kept constant as a whole by a temperature adjusting mechanism (not shown) installed in the stirring and mixing tank 10.

1, 2, and 4, the pipe from the in-tank liquid collection unit 13 to the liquid pressurizing mechanism 20 is not branched, but for example, the collection from one common in-tank liquid collection unit 13 The liquid E2 may be divided into two in the middle, and the liquid E2 may be divided into two liquid pressurization mechanisms 20 and pressurized separately. Further, the pressurized liquid that has passed through one pressurizing mechanism 20 may be divided into two and ejected from the two pressurized liquid ejecting units 14.

After depressurization, the temperature at which the pressurized liquid E3 is jetted and circulated into the stirring and mixing vessel 10 is not particularly limited as long as the agglomerates are sufficiently separated and refined, but the preferred temperature range is as described above. Street.
The time for which the pressurized liquid E3 obtained by continuously collecting the liquid E1 in the tank into the liquid pressurizing mechanism 20 after being decompressed or during the decompression is sprayed and circulated into the stirring and mixing tank 10 is as follows. There is no particular limitation as long as the agglomerates are sufficiently separated and refined, and depending on the amount of treatment, it is preferably 10 minutes to 5 hours, more preferably 20 minutes to 3 hours, more preferably 30 minutes to 2 hours. The following are particularly preferred:
When the time is equal to or more than the above lower limit, there are many injection opportunities, the injection is advantageous for a single batch, and the agglomerates are sufficiently separated and refined. On the other hand, if it is not more than the above upper limit, it is advantageous in terms of productivity and cost.
After reducing the pressure in the stirring and mixing tank 10 for a sufficient time, it may be injected / circulated under reduced pressure, or injection / circulation may be started simultaneously with the start of the pressure reduction, but the dissolved air is removed by reducing the pressure. Therefore, it is desirable to inject and circulate for the above time.

<Charging mechanism 40>
As shown in FIG. 4, an aqueous emulsion E collected when a charging mechanism 40 is provided between the in-tank liquid collection unit 13 and the liquid pressurizing mechanism 20 to continuously collect a part of the in-tank liquid E1. It is preferable to charge the collected liquid E2 using the charging mechanism 40.

By using the charging mechanism 40 to charge the fine particles in the aqueous emulsion E (collected liquid E2) and the surrounding surfactant, the aggregation of the fine particles can be suppressed by the electric repulsive force acting between the fine particles. it can. As a result, the dispersion state of the fine particles can be favorably maintained over a long period. When the dissolved air (oxygen) is exhausted by reducing the pressure, the bonds between water molecules are weakened, the above phenomenon is likely to occur, and the dispersibility is further improved.

The charging mechanism 40 is not provided between the in-vessel liquid collecting unit 13 and the liquid pressurizing mechanism 20. For example, the aqueous emulsion obtained after the completion of the treatment may be charged. When the charging mechanism 40 is provided between the liquid pressurizing mechanism 20 and charging is performed, charging is performed while the aqueous emulsion E is circulated, so that the above-described effect due to charging is easily achieved.

[Aqueous emulsion]
The “aqueous emulsion” in the present invention is not limited to a liquid dispersed in a liquid (water) but refers to a liquid or solid dispersed in water as a dispersion medium.
There is no limitation in particular in the kind of aqueous emulsion applied to this invention, According to the intended purpose, it selects suitably.

Examples of the aqueous emulsion in the present invention include, for example, acrylic emulsion, methacrylic emulsion, styrene emulsion, vinyl acetate emulsion, (anhydrous) maleic acid emulsion, alkylene emulsion, urethane emulsion and the like. In these, polymer particles (resin fine particles) obtained by mixing at least a hydrophobic polymerizable monomer and an emulsifier (surfactant), blending a water-soluble polymerization initiator, and emulsion polymerization are water. An aqueous emulsion dispersed in

There is no limitation in particular about the kind of emulsifier (surfactant) and a polymerization initiator, A well-known thing can be used.
As the emulsifier (surfactant), any of a cationic surfactant, an anionic surfactant, and a nonionic surfactant can be used.
About a polymerization initiator, a radical polymerization initiator is preferable and a thermal polymerization initiator is preferable.

In addition, the aqueous emulsion in the present invention is not limited to a simple emulsion polymerized one, but may be a polymer obtained by suspension polymerization, seed polymerization or the like. Moreover, what dispersed the microparticles | fine-particles prepared previously in water is also mentioned.

The aqueous emulsion whose dispersibility is improved by the method for improving dispersibility of the aqueous emulsion of the present invention exhibits excellent properties as described above when used as an aqueous paint for the reasons described above. The application target is not limited to paint. The method of the present invention, which can separate agglomerates in an aqueous emulsion and remove impurities, can be applied to uses such as inks, adhesives, cosmetics, and surface treatment agents.

When the aqueous emulsion of the present invention is used for the above-mentioned use, substances necessary for the use can be further added as appropriate.
Since the aqueous emulsion whose dispersibility is improved by the method for improving dispersibility of the aqueous emulsion of the present invention is preferably used for the above-mentioned applications, it is preferable that a pigment is blended.

When the pigment is blended, (A) the aqueous emulsion containing no pigment may be subjected to the treatment of the present invention, the pigment may be added to the aqueous emulsion obtained after the completion of the treatment, and the pigment may be dispersed by a known method. B) An aqueous emulsion to which a pigment has been added in advance may be added as a raw material and subjected to the treatment of the present invention. (C) The pigment is treated during the treatment of the present invention (for example, when dissolved air is removed by low-pressure stirring). May be added.
The above (A) is preferable in order to make the pigment finer by subjecting it to the method of the present invention, and the above (B) is preferable in order to improve the dispersibility of the pigment in the finally obtained aqueous emulsion. .

[Characteristics, effects, actions and principles of aqueous emulsion]
The aqueous emulsion whose dispersibility is improved by the method for improving dispersibility of the aqueous emulsion of the present invention is superior to conventional aqueous emulsions in terms of adhesion, toughness, weather resistance, heat resistance, odor and the like. Yes.
As described above, the water-based emulsion of the present invention is useful for applications such as water-based paints, adhesives, inks, cosmetics, and surface treatment agents. Aqueous paints containing the aqueous emulsions of the invention are particularly useful.
Since the water-based paint containing the water-based emulsion of the present invention exhibits excellent properties as described above, specifically, for rust prevention, antifouling, mildew prevention, insulation, heat insulation, snow prevention, etc. used.

The operation / principle of the present invention is not limited to the scope of the following description, but the following can be considered for the operation / principle of the present invention.

The present invention makes it possible to make individual agglomerates (or small agglomerates) by causing the agglomerates of fine particles contained in the aqueous emulsion to collide with the aqueous emulsion in the stirred and mixed tank under reduced pressure. It is separated and refined. At that time, “aggregates” or “aggregates and individual fine particles” collide, and the aggregates are separated and refined.
In the aqueous emulsion in the stirring and mixing tank, the dissolved air is removed and the bonding force between the fine particles is weakened. Small agglomerates) are separated and refined.
In fact, it has been confirmed by the present inventor that an aqueous emulsion from which dissolved air has been removed has a low expansion rate. Since the expansion rate is low, it is easy to pressurize, and it is considered that the collision energy of the pressurized aqueous emulsion contributed to separation and refinement efficiently.

That is, since the inside of the stirring and mixing tank is in a reduced pressure state, the dissolved air (oxygen) contained in the aqueous emulsion is removed from the aqueous emulsion, so that the binding force between the fine particles is reduced and the aqueous emulsion is added. By increasing the pressure effect, the collision energy is efficiently used for separation / miniaturization, and no external air pressure is applied from around the agglomerates, so separation / miniaturization is suitably performed.

It is considered that the temperature at the location where the pressurized liquid is injected into the stirring and mixing tank and collided with the liquid in the tank is extremely high locally (although not limited, for example, 100 ° C. or more and 400 ° C. or less). Further, as described above, a particularly preferable pressure of the pressurized liquid ejected from the pressurized liquid ejecting unit is 20.3 MPa (200 atm) or more and 25.3 MPa (250 atm). On the other hand, since the critical temperature and critical pressure of water are 374 ° C. and 22 MPa (218 atm), respectively, the location of the collision may be locally supercritical.
Since it is close to supercritical, the number of water molecules that form one water cluster decreases (small cluster water is generated), and fine particles with separated and refined aggregates enter between the water molecules. It is considered that fine particles were dispersed well.
Furthermore, it has been confirmed by the present inventor that when dissolved air is removed by reducing the pressure, the critical temperature of water is lowered. Therefore, it can be considered that the above phenomenon occurred more easily in the “pressurized liquid once decompressed” in the present invention.

In the present invention, a part of the aqueous emulsion (liquid in the tank) in the stirred and mixed tank in a reduced pressure state is continuously collected, and the collected aqueous emulsion (collected liquid) is pressurized and directed into the stirred and mixed tank. Since the jetting is performed, the aqueous emulsion is circulated in the apparatus, so that the collision can be repeated many times and the processing can be continuously performed.
The ease of formation and separation of agglomerates and the degree of aggregation depend on the type of resin fine particles, the type of additives such as polymerization initiators and surfactants; the processing conditions during stirring, pressurization, and jetting, etc. In a method such as Patent Document 2, depending on the conditions, the agglomerates may not be sufficiently separated in a single process, and it may be necessary to repeat the process over and over. To do. In this regard, in the method of the present invention, since the processing can be performed continuously, the input and extraction of the raw material can be performed only once, and therefore the agglomerates can be sufficiently separated by extending the processing time. As a result, it is possible to efficiently perform a large amount of processing.

[Water-based paint]
The kind of the water-based paint containing the water-based emulsion of the present invention is not particularly limited, and a substance to be blended in the water-based emulsion when the water-based paint is used is appropriately selected and blended according to the water-based paint.
The type of the water-based paint is not particularly limited, but is used for applications such as rust prevention, antifouling, antifungal, insulation, heat insulation, and prevention of snow accretion in order to exert the above-described effects of the aqueous emulsion of the present invention. It is preferable that the water-based paint is used.

[Characteristics, effects, actions and principles of water-based paints]
Water-based paints containing aqueous emulsions with improved dispersibility (separated and refined agglomerates) by the method of the present invention exhibit excellent adhesion and toughness (coating film hardness), but this is because fine particles are aggregated When a lump is formed, it contacts the coating material surface in the form of large agglomerates (FIG. 5 (a)), whereas when separated into individual particles, the coating material surface is in the form of individual particles. This is probably because the contact area is large.

Further, when the fine particles form an agglomerate (FIG. 5A), when the coating surface deteriorates due to ultraviolet rays or the like, the deterioration is chained to the lower part of the agglomerate (coating material surface). When separated into individual fine particles (FIG. 5 (b)), even if the fine particles on the coating surface deteriorate, no agglomerates are formed (or the size of the agglomerates is small). It is considered that the lower part (coating material surface) of the agglomerates is not deteriorated, and the water-based paint of the present invention is excellent in weather resistance.

The water-based paint of the present invention is excellent in terms of heat resistance and odor. This is presumably because unnecessary substances such as dissolved air (especially oxygen) and impurities in the water-based emulsion were removed by the reduced pressure treatment. Such unnecessary materials are preferably removed to separate and refine the agglomerates in order to strengthen the bonding force between the fine particles. However, if they remain in the coating film, the paint tends to burn. And cause odor. Moreover, such an unnecessary thing raises the electrical conductivity of a coating film and reduces rust prevention property. The point that such unnecessary materials are removed from the coating film is also an excellent point of the method of the present invention.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples and comparative examples as long as the gist thereof is not exceeded.

[Example 1]
As shown in FIG. 2, an aqueous emulsion is used by using an apparatus of a type in which a pressurized liquid injection unit 14 exists in the hollow portion 15 of the stirring and mixing tank 10 and makes the pressurized liquid E3 injected from two directions collide with each other. Was processed. The liquid pressurizing mechanism 20 was a cylinder 21 having a piston 22 as shown in FIG.

The volume of the stirring and mixing tank 10 was 1 m ³ . Into the stirring and mixing tank, 800 L of an acrylic emulsion (made by Nippon NS Co., Ltd., AD157), which is an aqueous emulsion, was charged.

The decompression mechanism 30 is started by using a vacuum pump to depressurize the stirring and mixing tank 10 so as to keep the stirring and mixing tank 10 at about 20 Torr (2.6 kPa). Stirring in the stirring and mixing tank 10 was started after maintaining the temperature uniformly at ° C.
Since the saturated vapor pressure of water at 20 ° C. is 17.5 Torr (2.3 kPa), the pressure in the stirring and mixing vessel 10 is maintained at a level slightly higher than the saturated vapor pressure of water.
Along with the reduced pressure, the level of the aqueous emulsion (liquid E1 in the tank) once increased, and it was confirmed that dissolved air (oxygen) was removed as bubbles, but the boiling of the aqueous emulsion (liquid E1 in the tank) It didn't happen.

While the pressure was reduced, the valve of the pipe connecting the stirring and mixing tank 10 and the liquid pressurizing mechanism 20 was opened, and a part of the liquid E1 in the tank was sent into the two liquid pressurizing mechanisms 20 respectively.
At that time, the charging mechanism 40 was activated, and the collected liquid fed into the liquid pressurizing mechanism 20 was charged.
The pressure of the pressurizing liquid E3 is set to 25.3 MPa (250 atm), and the pressurizing liquid E3 is substantially omitted from the two pressurizing liquid ejecting units 14 provided in the hollow portion 15 in the stirring and mixing tank 10. Sprayed in the horizontal direction, the pressurized liquids E3 collided with each other, and continuous processing was started.

After 1 hour, all the valves in the apparatus are closed, the vacuum pump, the liquid pressurizing mechanism 20 and the charging mechanism 40 are stopped, the processing is completed, and the take-out port located below the hollow portion 15 in the stirring and mixing tank 10 From 16, the aqueous emulsion after treatment was collected.

When the particle size distribution before and after the treatment was measured using a laser diffraction / scattering type particle size distribution measuring apparatus (manufactured by Nikkiso Co., Ltd., model MT3300), as shown in FIG. The particle size (FIG. 6 (b)) is significantly smaller than the particle size of the fine particles of the acrylic emulsion before the treatment (FIG. 6 (a)). The fine particles of the acrylic emulsion after the treatment by the method of the present invention It was a small agglomerate with fine particles and particle sizes not reaching 1 μm.

[Comparative Example 1]
Using the apparatus shown in FIG. 1 of Patent Document 2, the same acrylic emulsion 800L as in Example 1 was subjected to a treatment for separating the agglomerates into individual fine particles or small-sized agglomerates.
In the apparatus of Patent Document 2, (a) the step of stirring the aqueous mixed solution in a reduced pressure state and (b) the step of jetting and colliding the pressurized aqueous mixed solutions are performed by separate mechanisms (devices). The process is a batch device that is completely separated. Accordingly, the aqueous mixture after step (b) cannot be continuously processed by returning it to step (a).

The volume of the vacuum tank (corresponding to “stirring and mixing tank 10” in the apparatus of the present invention) was made substantially the same as in Example 1.
The pressure in the vacuum tank was kept at about 20 Torr (2.6 kPa), the temperature in the vacuum tank was kept uniform at 20 ° C., and stirring in the vacuum tank was started.

The acrylic emulsion is fed from the vacuum tank to the pressurizing chamber (corresponding to “liquid pressurizing mechanism 20” in the apparatus of the present invention), and the pressurizing pressure is set to 25.3 MPa (250 atm). The acrylic emulsions collided with each other.
The collided acrylic emulsion was stored in a storage container. It took 25 hours to accommodate all of the charged acrylic emulsion in the container.

When the particle size distribution of the acrylic emulsion fine particles before and after the treatment was measured by the same method as in Example 1, the particle size of the fine particles of the acrylic emulsion after the treatment was smaller than the particle size of the fine particles of the acrylic emulsion before the treatment. The agglomerates were separated and refined to some extent, but were larger than the particle diameter of the fine particles of the acrylic emulsion after the treatment in Example 1 (FIG. 6B).

As is clear from the above results, when the method for improving the dispersibility of the aqueous emulsion of the present invention is used, continuous treatment is possible by circulating the aqueous emulsion. Compared to the above, the dispersibility of the aqueous emulsion could be improved efficiently. Specifically, the time from when the raw acrylic emulsion was charged into the apparatus until the treated acrylic emulsion was taken out could be reduced to 1/25.
Further, the particle diameter of the fine particles in the acrylic emulsion after the treatment could be made smaller (good dispersibility) when treated by the method of the present invention.

The water-based emulsion improved in dispersibility using the method for improving dispersibility of the aqueous emulsion of the present invention (separated and refined agglomerates) has an adhesive property, toughness, weather resistance, heat resistance, odor property, etc. Excellent in terms, it is widely used in applications such as water-based paints, adhesives, inks, cosmetics, etc. Especially as water-based paints, rust prevention, antifouling, mold prevention, insulation, heat insulation, snow prevention For example, it is widely used for application to an object to be coated.

DESCRIPTION OF SYMBOLS 1 Dispersibility improvement apparatus 10 Stirring mixing tank 11 Stirring mechanism 12 Exhaust part 13 In-vessel liquid collecting part 14 Pressurized liquid injection part 15 Recessed part 16 Outlet 20 Liquid pressurizing mechanism 21 Cylinder 22 Piston 30 Depressurization mechanism 40 Charging mechanism E Aqueous Emulsion E1 In-tank liquid E2 Collected liquid E3 Pressurized liquid α Injection direction of pressurized liquid on the horizontal plane

Claims (9)

1. A method for improving the dispersibility of an aqueous emulsion, wherein the inside of a stirring and mixing tank charged with an aqueous emulsion is decompressed to a pressure at which dissolved air contained in the aqueous emulsion is removed, and the aqueous emulsions after the decompression treatment collide with each other. ,
   A part of the liquid in the tank, which is an aqueous emulsion existing in the stirring and mixing tank, is continuously collected in a liquid pressurizing mechanism, and the pressurized liquid, which is an aqueous emulsion pressurized by the liquid pressurizing mechanism, is The water-based emulsion is circulated by spraying from the nozzle-shaped pressurized liquid spraying section having an inner diameter of 0.03 mm to 0.3 mm toward the stirring and mixing tank,
   Dispersibility of an aqueous emulsion characterized by improving the dispersibility of fine particles in the aqueous emulsion by colliding with the liquid in the tank when the pressurized liquid is jetted into the stirring and mixing tank Improvement method.
2. The method for improving the dispersibility of an aqueous emulsion according to claim 1, wherein the speed of the pressurized liquid immediately after being ejected from the pressurized liquid ejecting section is 50 m / s or more and 1500 m / s or less.
3. The method for improving the dispersibility of an aqueous emulsion according to claim 1 or 2, wherein the pressure of the pressurizing liquid when sprayed from the pressurizing liquid ejecting section is 3 MPa or more and 250 MPa or less.
4. The method for improving dispersibility of an aqueous emulsion according to any one of claims 1 to 3, wherein the stirring and mixing tank has a hollow portion, and the pressurized liquid is injected into the hollow portion.
5. The method for improving the dispersibility of an aqueous emulsion according to claim 4, wherein the dent is present in the lower part of the stirring and mixing tank.
6. The method for improving the dispersibility of an aqueous emulsion according to claim 4 or 5, wherein the pressurized liquid is sprayed from at least two directions into the hollow portion, and the pressurized liquids sprayed from different directions collide with each other. .
7. The method for improving the dispersibility of an aqueous emulsion according to claim 6, wherein the injection direction of the pressurized liquid in the recessed portion is substantially horizontal or obliquely upward with respect to a horizontal plane.
8. The aqueous solution according to any one of claims 1 to 7, wherein a collected liquid that is an aqueous emulsion collected when a part of the liquid in the tank is continuously collected is charged using a charging mechanism. Method for improving dispersibility of emulsion.
9. A method for producing an aqueous emulsion, characterized in that the method for improving the dispersibility of an aqueous emulsion according to any one of claims 1 to 8 is used.

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