JPH05184895A - Emulsion manufacturing method - Google Patents

Abstract

PURPOSE:To produce an emulsion with the diameters of the micelles in the dispersed phase uniformized even when the micelle is relatively large and the concn. is high. CONSTITUTION:A liq. to constitute a dispersed phase is passed through a microporous membrane 1 having micropores and formed into a liq. to constitute a continuous phase to produce an emulsion. In this case, 100-150% of the absolute minimum of the surfactant is added to the continuous phase to stabilize the emulsion which is being successively formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing various emulsions such as O / W type and W / O type, and more particularly to a method for producing emulsions having a uniform particle size.

[0002]

2. Description of the Related Art As a method for producing an emulsion having dispersed phase particles having a uniform particle size, Japanese Patent Application Laid-Open No. 2-95433 discloses a microporous membrane having a liquid as a dispersed phase and having fine pores of uniform pore size. There is disclosed a method in which the dispersed phase is dispersed as fine particles in the continuous phase by press-fitting into the liquid serving as the continuous phase. According to the method described in this publication, an emulsion in which the dispersed phase particles have a relatively uniform particle size can be obtained.

For example, when an emulsion production apparatus as shown in FIG. 1 is used to produce an emulsion according to the method described in the above publication, the following procedure is carried out. First, the MPG module 2 is equipped with the microporous membrane body 1 having a uniform pore size and more easily wetted by the continuous phase than the dispersed phase. The continuous phase enters the inside of the microporous membrane body 1 in the MPG module 2 from the continuous phase circulation tank 5 through a line 7 equipped with a pump 6, and circulates through a line 10 equipped with a pressure gauge 8 and a flow meter 9. is doing. The dispersed phase receives a pressure from a line 13 equipped with a nitrogen cylinder 11 and a pressure tank 12, enters the MPG module 2 from the dispersed phase tank 3 through a line 4, and is extruded from the outer side to the inner side of the microporous membrane body 1. As a result, the continuous phase is pressed into the circulating microporous membrane 1. When the dispersed phase is pressed into the continuous phase as described above, an emulsion in which dispersed phase particles are dispersed in the continuous phase starts to be formed, and the emulsion enters the continuous phase circulation tank 5 through the line 10. Although the concentration of the emulsion is low at the beginning of production, the concentration gradually increases during repeated circulation along with the continuous phase in the above circulation path (continuous phase circulation tank 5-line 7-inside of microporous membrane body 1-line 10). Eventually, the desired concentration is reached. The produced emulsion is taken out from the continuous phase circulation tank 5 through the outlet 15.

When an emulsion is produced by the above method, an emulsion having a narrow particle size distribution and a uniform particle size is obtained when the dispersed phase particles have a relatively small particle size or when the concentration of the emulsion is relatively low. .. However, when an emulsion having a relatively large particle size or an emulsion having a small particle size and a high concentration is produced, there is a drawback that an emulsion having a narrow particle size distribution cannot be stably obtained. all right. The reason for this is that in the above method, the generated dispersed phase particles are always subjected to a shearing force in the circulation path of the continuous phase, and therefore, during the circulation, the dispersed phase particles may be split again. It seems to be because. When it is desired to obtain an emulsion having a large particle size of dispersed phase particles and an emulsion having a high concentration which requires long-term operation, it is susceptible to the influence. Therefore, the dispersed phase particles (hereinafter, It is assumed that finer dispersed phase particles (hereinafter referred to as secondary particles) are more likely to be generated by further splitting of primary particles.

The particle size of the dispersed phase particles and the concentration of the emulsion will vary depending on the properties required for the emulsion and the application of the emulsion. The particle size and the concentration of the emulsion are required in a wide range, and for economic reasons, particularly in the case of producing an industrial product, a high concentration is required, and an emulsion having a uniform particle size is required. Has been done.

[0006]

SUMMARY OF THE INVENTION The present invention provides a method for producing an emulsion in which the dispersed phase particles have a uniform particle size even when the dispersed phase particles have a relatively large particle size and the emulsion concentration is high. The purpose is to provide.

[0007]

DISCLOSURE OF THE INVENTION As a result of studying the method described in the above publication, the present inventor has found that the amount of the dispersed phase is much larger than the minimum amount necessary for stabilizing the primary particles. It was found that a large amount of secondary particles are generated due to the shearing force when present in the inside. And a state in which there is no excess of surfactant in the dispersed phase above the minimum amount,
That is, it was found that in the state where no free surfactant is present in the dispersed phase, even if the above-mentioned shearing force acts on the primary particles, the splitting thereof is less likely to occur and the secondary particles are less likely to occur.

The method for producing an emulsion of the present invention is a method for producing an emulsion in which a liquid to be a disperse phase is pressed into a liquid to be a continuous phase through a microporous membrane having pores. The minimum amount of 100-150 required to stabilize the emulsion
% Surfactant is added to the continuous phase,
Thereby, the above object is achieved.

The present invention will be described in detail below.

The present invention can be carried out using the apparatus of FIG. 1, in which the continuous and dispersed phase circulation paths are similar to those of the prior art described above.

As the surfactant used in the present invention, any of anionic surfactants, cationic surfactants and nonionic surfactants can be used.

Examples of the anionic surfactant include alkyl sulfates, polyoxyethylene alkyl ether sulfates, N-acyl amino acid salts, polyoxyethylene alkyl ether acetates, alkyl sulfocarboxylates and the like.

Examples of the cationic surfactant include alkylammonium salt, alkylbenzylammonium salt, betaine, imidazolium betaine, lecithin and the like.

Examples of the nonionic surfactant include sorbitan fatty acid ester, glycerin fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether and the like.

In the present invention, the minimum amount of the surfactant necessary to stabilize the primary particles is determined from the results obtained by analyzing the experimental data as follows.

The total surface area S _t of the dispersed phase particles dispersed in the continuous phase is determined, and this is the area occupied by the surface of the dispersed phase particles when one molecule of the surfactant is coordinated with the dispersed phase particles (hereinafter, By dividing by the surfactant coordination area) f,
The required number of surfactant molecules, N, is determined. Since it is required the number of moles of surfactant needed by dividing the number of molecules N in Avogadro's number ^{_{(N A = 6.022 × 10 23}} ), the required surface when multiplied by the molecular weight of the surfactant to the number of moles The weight (g) of activator is determined. Specifically, it becomes like the following formula [I].

[0017]

[Equation 1]

The total surface area S _t of the dispersed phase particles dispersed in the continuous phase is determined by (surface area S _{1 of} dispersed phase particles × total dispersed phase particle number n).

The total dispersed phase particle number n is calculated by (total volume of the dispersed phase particles V ÷ dispersed phase particles one volume V _1), the total volume V is (weight of the dispersed phase w ÷ dispersed phase of the dispersed phase particles Specific gravity d) of That is,

[0020]

[Equation 2]

Since the unit of V is ml, this is converted to cubic angstrom and the particle diameter of the dispersed phase is D angstrom, the above formula [II] becomes the following formula [II] '.

[0022]

[Equation 3]

Substituting this formula [II] 'into the above formula [I],
When arranged, it becomes as follows, and the following formula [I] 'is obtained.

[0024]

[Equation 4]

The surfactant coordination area f is in the range of approximately 20 to 50 sq. Angstroms, although it varies depending on the kind of the surfactant.

The surfactant is added to the continuous phase in the range of 100 to 150% of the minimum amount calculated by the above calculation. That is, the particle size of the dispersed phase particles and the total weight of the dispersed phase particles in the emulsion that is sequentially produced by press-fitting the dispersed phase into the continuous phase are measured, and the minimum amount is calculated from the above formula [I] '. , Sequentially adding surfactant to the continuous phase such that 100-150% of it is contained in the continuous phase. A particularly preferable range is 100 to 130%. If it is added in excess of the above minimum amount of 150%, secondary particles may be generated.

The above surfactant is used in the device of FIG.
Usually, it is added to the continuous phase in the continuous phase circulation tank 5 by a metering pump (not shown). The method of adding the surfactant is
A continuous addition method in which a fixed amount is continuously added to the continuous phase throughout the production of the emulsion, and the total amount of the surfactant is divided into several batches, which are intermittently divided into several batches before and during the production of the emulsion. Either of the divided addition methods to be added can be selected. In case of split addition method, the total amount is 5
% Is preferably added to the continuous phase before the start of production and the rest in proportion to the concentration of the emulsion formed.
When the divided addition method is used, the particle size of the obtained emulsion may not be uniform if the number of divisions such as two divisions is rough, so the larger the number of divisions, the more preferable.

[0028]

【Example】

(Example 1) An O / W type emulsion was produced using the apparatus shown in FIG. As the microporous membrane body 2, an inorganic microporous membrane body (pore size 1.25 μ) was used. As the dispersed phase,
300 g of a mixture of 50 parts by weight of divinylbenzene (commercial product containing 50% of divinylbenzene and 50% of ethylvinylbenzene), 49 parts by weight of tetramethylolpropane tetraacrylate, and 1 part by weight of benzoyl peroxide as a polymerization catalyst was used. The specific gravity of this mixture is 1.02. Sodium dodecylbenzene sulfonate (hereinafter referred to as DBS) was used as a surfactant.
The amount W (g) of DBS necessary for stabilizing 300 g of the mixture to a particle size of 7 μ and stabilizing it was calculated by the above formula [I] '(molecular weight of DBS: 348, coordination area of DBS: 30). Square angstrom),

[0029]

[Equation 5]

Therefore, the amount of DBS added should be 0.503.
g and dissolved in 100 g of water to give an aqueous solution.

After adding 3000 g of water to the continuous phase circulation tank 5 and putting 300 g of the mixture into the dispersed phase tank 3, the continuous phase was circulated at a flow rate of 3 m / sec, and the flux of the dispersed phase was 3
Pressure of 0.40k in dispersed phase so that g / cm ² · hr
The production of the emulsion was started by applying g / cm ² . At the same time, the DBS aqueous solution was added to the continuous phase circulation tank 5 at 50 ml / hr using a metering pump (not shown). The rate of press-fitting of the dispersed phase into the continuous phase and the rate of addition of the surfactant to the continuous phase were as shown in Table 1 below.

[0032]

[Table 1]

After 2 hours, 3400 g of an emulsion containing 300 g of dispersed phase were obtained.

The average particle size of the obtained emulsion is 7.0.
The particle size distribution was 9μ, the standard deviation of the particle size distribution was 1.50, and the CV value (CV value = standard deviation / average particle size) was 21.2%.

The emulsion obtained above was placed in a separable flask having an internal volume of 5 liters, and a polymerization reaction was carried out at 80 ° C. for 5 hours while gently stirring, and further heated at 90 ° C. for 5 hours to complete the polymerization reaction. .. After the polymerization, the obtained polymer was washed and dried. FIG. 2 is an electron micrograph showing the particle structure of the obtained polymer. From FIG. 2, it can be seen that there are almost no secondary particles.

(Comparative Example 1) 0.503 g of DBS,
The same procedure as in Example 1 was repeated except that the emulsion was dissolved in 3000 g of water before starting the production and placed in the continuous phase circulation tank 5.
3300 g of an emulsion containing 300 g of dispersed phase were obtained. The average particle size of the obtained emulsion was 5.17μ,
The standard deviation of the particle size distribution was 1.99 and the CV value was 38.5%.

The emulsion obtained above was polymerized in the same manner as in Example 1. FIG. 3 is an electron micrograph showing the particle structure of the obtained polymer. It can be seen that the number of secondary particles is large as compared with FIG.

(Example 2) An inorganic microporous membrane (pore size 2.24μ) was used as the microporous membrane 2 and Example 1 was used.
The same amount of the dispersed phase used in Example 1 was used as in Example 1, and the particle size was 12.0.
A μ emulsion was prepared. The same DBS as in Example 1 was used as the surfactant. The weight of DBS required to stabilize the emulsion having a particle size of 12.0 μ is 0.283 g when calculated in the same manner as in Example 1. 0.297 g of 1.05 times this amount was dissolved in 105 g of water to obtain an aqueous solution. 5 g of this DBS aqueous solution was put into the continuous phase circulation tank 5 together with 2595 g of water. After putting 300 g of the mixture that becomes the dispersed phase in the dispersed phase tank 3, the continuous phase is flowed at 2.7
Circulating at m / sec, the dispersed phase flux is 2.7 g
Pressure of 0.043k in the dispersed phase so that it becomes / cm ² · hr
Emulsion production was started by applying g / cm ² . At the same time, the remaining DBS aqueous solution was added to the continuous phase circulation tank 5 at 50 ml / hr using a metering pump (not shown).

After 2 hours, 3000 g of an emulsion containing 300 g of dispersed phase were obtained.

The average particle size of the dispersed phase particles of the obtained emulsion was 12.1 μ, the standard deviation of the particle size distribution was 3.90, C
The V value was 32.3%.

The emulsion obtained above was polymerized in the same manner as in Example 1. FIG. 4 is an electron micrograph showing the particle structure of the obtained polymer. From FIG. 4, it can be seen that there are almost no secondary particles.

Comparative Example 2 An emulsion containing 300 g of the dispersed phase was prepared in the same manner as in Example 2 except that 0.347 g of DBS was dissolved in 2700 g of water before starting the emulsion production and placed in the continuous phase circulation tank 5. 3000 g were obtained. The average particle size of the dispersed phase particles of the obtained emulsion was 6.73 μ, the standard deviation of the particle size distribution was 4.63, and the CV value was 68.8%.

The emulsion obtained above was polymerized in the same manner as in Example 1. FIG. 5 is an electron micrograph showing the particle structure of the obtained polymer. It can be seen that there are many secondary particles as compared with FIG.

[0044]

According to the production method of the present invention, even if the particle size of the dispersed phase particles is relatively large or the concentration of the emulsion is considerably high, the dispersed phase particles do not divide,
It is possible to produce an emulsion in which the dispersed phase particles have a uniform particle size.

The production method of the present invention can be used in the industry for producing various emulsions which require a uniform particle size. For example, polymer emulsions, uniform particle toners, and high-concentration oil and fat emulsions can be produced. It can be used in all fields such as manufacturing.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an emulsion production apparatus used in the present invention.

FIG. 2 is an electron micrograph showing a particle structure of a polymer obtained by polymerizing the emulsion prepared in Example 1.

FIG. 3 is an electron micrograph showing a particle structure of a polymer obtained by polymerizing the emulsion prepared in Comparative Example 1.

FIG. 4 is an electron micrograph showing a particle structure of a polymer obtained by polymerizing the emulsion prepared in Example 2.

5 is an electron micrograph showing the particle structure of a polymer obtained by polymerizing the emulsion prepared in Comparative Example 2. FIG.

[Explanation of symbols]

 1 Microporous membrane 3 Dispersed phase tank 5 Continuous phase circulation tank

Claims (1)

[Claims] 1. A method for producing an emulsion by press-fitting a liquid to be a dispersed phase into a liquid to be a continuous phase through a microporous membrane having pores, in order to stabilize emulsions successively produced. A method for producing an emulsion, characterized in that a minimum amount of 100-150% of a surfactant required for the above is added to the continuous phase.