JPH0549912A - Production of microcapsule - Google Patents

Abstract

PURPOSE:To obtain a method for producing a microcapsule capable of obtaining a uniform particle size distribution. CONSTITUTION:A disperser is equipped with both a cylindrical stator 4 having a projectionlike edge in the inner wall and a cylindrical rotor 5 which is provided to the inside of the stator 4 and has the projectionlike edge in the outer wall. Shearing force is given to the liquid passed through the interval between the stator 4 and the rotor 5 by rotating the rotor 5. Hydrophobic liquid is emulsified and dispersed into the hydrophilic liquid by this disperser. Thereby a microcapsule is produced in which a wall film including emulsified and dispersed hydrophobic droplets is 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 microcapsules used for pressure-sensitive copying sheets and the like, and more particularly to a method for producing microcapsules capable of obtaining a uniform particle size distribution.

[0002]

BACKGROUND OF THE INVENTION Pressure sensitive copying sheets are placed on two separate webs.
Recording is obtained by combining sheets on which seed coating layers are formed. One of them is a microcapsule-containing layer containing a hydrophobic liquid in which a color former such as a basic leuco dye is dissolved. The other is a developer-containing layer, which is formed on another web facing the capsule layer. Then, the capsule is broken by external pressure, the hydrophobic liquid in the capsule is caused to flow out, and it is reacted with the developer to obtain a color image. Blue, red,
The hue such as black is selected depending on the type of dye.

Also, by inserting a required number of middle sheets of paper, each of which has a coloring agent-containing layer coated on the front surface of the base paper and a microcapsule-containing layer on the back surface thereof, are inserted between the upper and lower sheets, a large number of sheets are formed. Copies can also be obtained. In addition, a so-called single pressure-sensitive copy sheet in which the above-mentioned microcapsules and a coloring agent are formed as a laminated or mixed layer is also used as a kind of pressure-sensitive copy sheet.

In the production of microcapsules, the average particle size is adjusted to a certain value. However, if many microcapsules larger than the standard particle size are contained, the capsules will be broken due to handling during handling and the color developer will be included. There was the drawback of producing colored stains on the layer. On the other hand, if the particle size of the microcapsules is small, the color development performance deteriorates. Therefore, it is desirable that the majority of the capsule sizes be uniform with respect to the target particle size.

The step of dispersing the hydrophobic liquid is the most important step because it is the step of determining the particle size distribution of the microcapsules. Conventionally, attempts to make the capsule particle size distribution uniform have been made in JP-A-56-147627 and JP-A-58.
-40142, JP-A-58-202034, JP-A-59-87036, JP-A-2-160579 and the like.

[0006] These proposals use a disperser called an emulsifier, which has a rotor (1) having 4 to 5 blade blades and a substantially conical recess matching the rotor. , A stator (3) provided with several holes (2) facing the blades (see FIG. 4). Then, by rotating the rotor (1), a shearing force was generated in the gap between the rotor (1) and the stator (3) to emulsify and disperse the hydrophobic liquid in the hydrophilic liquid.

There are two kinds of such methods, one is a batch method, in which a rotor and a stator are set in a tank, and the rotor is rotated by a motor. Emulsification was carried out by dispersing the mixed solution in the tank for a certain period of time. In the batch system, in order to promote the circulation of the liquid, the same angle and twist as the blades inside the centrifugal pump were added to the stator to secure a flow rate of several 100 l / min and to perform circulation dispersion.

On the other hand, the continuous type is illustrated in FIG. 4, in which the rotor (1) and the stator (3) are not put in the liquid in the tank, but the rotor (1) and the stator (3) are in a cylinder. It is a method of carrying out dispersion emulsification by introducing a mixed liquid which is dispersed in a tube into a disperser. In this case, it is common practice to put several rotors and a set of stators in a cylinder in order to increase the dispersion efficiency, and to provide a circulation line to increase the number of times of shearing. A blade-like twist is added to secure a flow rate of several hundred liters / minute and the number of times of shearing is increased. However, even if such means is taken, the number of times of shearing with respect to the liquid is not uniform, so the particle size distribution is wide, and only microcapsules with a particle size distribution within a wide range of several% to several hundred% of the target particle size can be obtained. I couldn't do it.

This is due to the fact that the shearing frequency of the disperser is smaller than that of the liquid to be dispersed, while at the other part of the dispersion liquid, shearing force is applied many times due to circulation, and the target is obtained. The particle size is much smaller than the particle size. For this reason, there is no other way but to manage the target particle diameter by the average value of the respective particle diameters, and the conventional method has a problem in the stability of the quality of the pressure-sensitive recording sheet.

[0010]

DISCLOSURE OF THE INVENTION The present invention relates to a microcapsule granulation process for a pressure-sensitive copying sheet, in which the capsule particle size is made uniform and the color development performance is stabilized, and the generation of stains due to the large particle size microcapsule, and It is intended to provide a method for producing microcapsules having extremely stable color development performance without deterioration in color development ability due to microcapsules having a small particle size.

[0011]

The present invention comprises a stator having a cylindrical shape and a protruding blade on the inner wall thereof, and a cylindrical rotor having an inner wall and a protruding blade on the outer wall thereof. By rotating the emulsion, the hydrophobic liquid is emulsified and dispersed in the hydrophilic liquid by the disperser that applies shearing force to the liquid passing through the space between the stator and the rotor, and the wall film encapsulating the emulsified and dispersed hydrophobic droplets. It is a method for producing microcapsules for forming.

Further, according to the present invention, the inner blade of the stator and the protruding blades of the outer wall of the rotor are each in the shape of a truncated pyramid, and the interval between the convex portion of the blade of the inner wall of the stator and the concave portion of the blade of the outer outer wall of the rotor, and the outer wall of the rotor. The method for producing the above microcapsules is characterized in that the interval between the convex portion of the blade and the concave portion of the blade on the inner wall of the stator is 0.1 to 1.0 mm, and the outer circumference of the rotor rotates at a speed of 10 to 25 m / sec.

Further, the shaft of the stator is installed substantially vertically, and the hydrophobic liquid and the hydrophilic liquid are sent from the lower part of the stator, and the liquid is sheared while moving upward in the interval between the stator and the rotor. Disclosed is a method for producing the above-mentioned microcapsules which are emulsified and dispersed by receiving a force. Furthermore, the above-mentioned method for producing microcapsules is disclosed, in which the stator has a jacket structure that allows a refrigerant to pass therethrough, and emulsification and dispersion are performed while cooling the inside of the disperser.

According to the present invention, the hydrophobic liquid contains a color former,
Disclosed is a method for producing the above microcapsules, wherein the microcapsules are for a pressure-sensitive copying sheet.

[0015]

[Function] There are various methods for microencapsulation. Among them, the microcapsule having the synthetic resin wall film is
It is preferable in terms of capsule strength and ease of capsule preparation.
Examples of the resin forming the wall film include aminoaldehyde resin, polyurea resin, polyurethane resin, polyamide resin and the like.

Capsules having an aminoaldehyde resin wall membrane can be prepared, for example, from at least one amine such as urea, thiourea, alkylurea, ethyleneurea, acetoguanamine, benzoguanamine, melamine, guanidine, biuret and cyanamide, and formaldehyde, It is produced by an in-situ polymerization method using at least one aldehyde such as acetaldehyde, paraformaldehyde, hexamethylenetetramine, glutaraldehyde, glyoxal, and furfural, or an initial condensation product obtained by condensing them.

Polyurethane resin and polyurea resin wall membrane capsules use, for example, polyisocyanate and water, polyisocyanate and polyol, isothiocyanate and water, isothiocyanate and polyol, polyisocyanate and polyamine, and isothiocyanate and polyamine. Manufactured by the interfacial polymerization method. The polyamide resin wall membrane capsule is manufactured by an interfacial polymerization method of acid chloride and amine.

The dispersion method of the present invention can be applied to the encapsulation of a wall film as described above, but since the time required for dispersion is extremely short, encapsulation by the interfacial polymerization method in which the capsule quality is likely to change with long-term dispersion. Especially useful for. For example, in the method for producing a polyurethane resin, a polyurea resin, a polyurea urethane resin wall membrane capsule, a mixed liquid of a hydrophobic liquid in which a color former such as a leuco dye is dissolved and a polyvalent isocyanate is added to a hydrophilic liquid containing an emulsifier, and a preliminary liquid is added. After stirring, the mixture is put into the disperser of the present invention.

Alternatively, a fixed amount of two kinds of a mixed liquid of a hydrophobic liquid in which a leuco dye or the like is dissolved and a polyvalent isocyanate and a hydrophilic liquid containing an emulsifier may be simultaneously charged into the disperser used in the present invention. .. However, in the granulation process,
It is most important to uniformly disperse and emulsify the two liquids so that a large number of particles are contained in a target particle size, for example, in the range of 3 to 20 μm. However, in the conventional method in which a large volume of liquid flow is introduced between the rotor and the stator and dispersed by shearing force (Fig. 4), the force for dispersing the liquid is very rough, and the particle size is changed by dispersion emulsification of the liquid. I couldn't make it uniform. Therefore, a circulation method was used to increase the number of passages and to make the particles uniform.As a result, the particle size distribution should be widely distributed from a fine particle size to an extremely large particle size, and emulsified to a uniform particle size. I couldn't.

In the present invention, it is usually unnecessary to increase the number of shears by circulation. A description will be given below with reference to FIG. A relatively small volume of the two liquids is continuously charged into the granulation disperser, for example, from the bottom, and the liquids form a uniform liquid film on the inner wall of the stator (4) by the centrifugal force of the rotor. Moreover, the liquid film continuously advances upward along the inner wall of the stator due to the continuously injected liquid pressure. On the inner wall of the stator, for example, a large number of truncated pyramid-shaped blades are arranged at regular intervals, and preferably, they pass between the blades arranged on the outer periphery of the rotor (5) so as to maintain a constant gap with the blades. It will be a matter. FIG. 2 shows a state in which the rotor (5) is extracted from the stator (4). In FIG. 2, the protruding blade is partially omitted.

The shape of the blade is not limited to the truncated pyramid, but includes a truncated cone, a polygonal pyramid, and the like. The liquid passing through the gap between the stator and the rotor blade is subjected to shearing force by the blades arranged on the stator and rotor because the rotor is rotating in the circumferential direction at high speed. It is dispersed finely one after another. The particle size can be accurately controlled by increasing or decreasing the passing flow rate or changing the rotor rotational speed for the purpose of increasing or decreasing the shearing frequency. The interval between the projecting blade of the stator and the projecting blade of the rotor is shown in FIG. 3, but the interval is preferably 0.1 to 1.0 mm, more preferably 0.3 to 1.0 mm.

The speed of the outer circumference of the rotor is 5 to 25 m / sec.
Preferably about 10 to 20 m / sec
It is a degree. Thus, in the present invention, the particle size can be easily controlled, and adjustment to the target particle size is easy. Also,
This disperser has a characteristic that the number of shears per unit volume is the same as that of the passing liquid due to its structure, so that the majority of the particle diameters are uniform. If the temperature rises during the dispersion, the hydrophobic liquid inside is activated and the particle size becomes finer. However, cooling makes it easier to control the particle size.

The embodiment having the cooling jacket (6) in the stator portion is preferable for adjusting the temperature, and the cooling efficiency is high because the blade of the inner wall of the stator increases the cooling surface area. In the present invention, since the particle size can be uniformly controlled in the dispersion and emulsification steps, the stain coloration due to the large particle size capsule and the decrease in coloration due to the small particle size are eliminated.
A pressure-sensitive copy sheet with stable color development performance can be obtained.

The particle size of the capsule for the pressure-sensitive copying sheet cannot be generally stated depending on the film material, the film thickness, etc., but in the case of a synthetic resin film, it is, for example, about 3 to 20 μm. In the case of pressure-sensitive copying paper, the ratio within ± 20% of the target average particle size is
About 65% or more is preferable. For this purpose, it is preferable to appropriately adjust the peripheral speed, the blade interval, the flow rate, and the like.

The color forming agent is not particularly limited, but may be triphenylmethane / phthalide type, fluorane type, phenothiazine type, phenoxydine type, rhodamine lactam type,
Examples thereof include basic leuco dyes such as triphenylmethane type, diphenylmethane type, spiropyran type and indolylphthalide type. Examples of the hydrophobic liquid include cottonseed oil, hydrogenated terphenyl, hydrogenated terphenyl derivative, alkylbiphenyl, alkylnaphthalene, diarylalkane, kerosene, paraffin, naphthene oil, dibasic acid ester such as phthalic acid ester, etc., natural or synthetic. One or more of the above hydrophobic liquids are used.

As the emulsifier to be contained in the hydrophilic medium, various anions, nonions, cations, or amphoteric water-soluble polymers are used. Examples of the anionic polymer include gum Arabic, carrageenan, sodium alginate, pectic acid, tragacanth gum, almond gum having —COO ⁻ , —SO ₃ ⁻ and —OPO ₃ ^— groups.
Natural polymers such as agar, carboxymethylcellulose, sulfated cellulose, sulfated methylcellulose, carboxydimethylated starch, phosphorylated starch, semi-synthetic polymers such as ligninsulfonic acid, maleic anhydride type (including hydrolyzed ones) Polymers, acrylic acid-based, methacrylic acid-based or crotonic acid-based polymers and copolymers, vinylbenzenesulfonic acid-based or 2-acrylamido-2-methyl-
Propane sulfonic acid-based polymers and copolymers, and synthetic polymers such as polymers, partial amides or partially esterified products of such copolymers, carboxy modified polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol, phosphoric acid modified polyvinyl alcohol, etc. Is mentioned.

More specifically, the maleic anhydride-based (including hydrolyzed) copolymers include methyl vinyl ether-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, vinyl acetate-anhydrous. Maleic acid copolymers, methacrylamide-maleic anhydride copolymers, isobutylene-maleic anhydride copolymers and the like can be mentioned, as acrylic acid-based copolymers, methacrylic acid-based copolymers or crotonic acid-based copolymers. Is a methyl acrylate-acrylic acid copolymer (hereinafter "copolymer" is abbreviated) ethyl acrylate-acrylic acid, methyl acrylate-methacrylic acid,
Methyl methacrylate-acrylic acid, methyl methacrylate-methacrylic acid, methyl acrylate-acrylamide-
Acrylic acid, acrylonitrile-acrylic acid, acrylonitrile-methacrylic acid, hydroxyethyl acrylate-acrylic acid, hydroxyethyl methacrylate-methacrylic acid, vinyl acetate-acrylic acid, vinyl acetate-methacrylic acid, acrylamide-acrylic acid, acrylamide-methacrylic acid, methacrylic Amide-acrylic acid,
Examples of the copolymer include methacrylamide-methacrylic acid, vinyl acetate-crotonic acid, and the like. As the vinylbenzenesulfonic acid-based or 2-acrylamido-2-methyl-propanesulfonic acid-based copolymer, methyl acrylate-
Vinylbenzenesulfonic acid (or its salt) copolymer, vinyl acetate-vinylbenzenesulfonic acid copolymer, acrylamido-vinylbenzenesulfonic acid copolymer, acryloylmorpholine-vinylbenzenesulfonic acid copolymer, vinylpyrrolidone-vinylbenzene Examples thereof include sulfonic acid copolymers and vinylpyrrolidone-2-acrylamido-2-methyl-propanesulfonic acid copolymers.

Examples of the nonionic polymer include --OH.
Examples thereof include semi-synthetic polymers such as hydroxyethyl cellulose, methyl cellulose, pullulan, soluble starch, and oxidized starch having groups, and synthetic polymers such as polyvinyl alcohol. Examples of the cationic polymer include cation-modified polyvinyl alcohol. .. Further, examples of the amphoteric polymer include gelatin and the like.

From the formed microcapsule dispersion,
When preparing microcapsule-containing paints, if necessary, water-soluble polymers such as starches, polyvinyl alcohols, cellulose derivatives, carboxylic acid polymers and the like, acrylate ester-based, vinyl acetate-based, vinyl chloride-based, styrene -Binders such as butadiene type and natural rubber type latex are used. Further, a capsule protective agent such as starch particles or cellulose powder may be added. As the support, paper, film, synthetic paper or the like is used.

Examples of the coloring agent used for producing the self-coloring type pressure-sensitive copying paper include clay substances such as attapulgite, acid clay and activated clay, phenol resin and metal salts of aromatic carboxylic acid. The capsule-containing layer is formed by a coating machine such as an air knife coater or a blade coater, or a printing method. The above has been described in the case of obtaining a pressure-sensitive copy sheet so that the effects of the present invention can be easily understood, but the present invention is not limited to this, and examples thereof include toners, dyes, pharmaceuticals, fragrances, and cosmetics.
It goes without saying that it can also be applied as a method for producing various microcapsules for adhesives, agricultural chemicals, fuels, liquid crystals, surfactants and the like.

[0031]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited thereto, and unless otherwise specified, parts and% in the examples are parts by weight and parts by weight, respectively. % Is shown.

Example 1 Diisopropylnaphthalene (trade name: K-113, manufactured by Kureha Chemical Co., Ltd.) was added with 5% of crystal violet lactone as a coloring agent, and polymethylene polyphenyl isocyanate as a wall film agent (trade name: Millionate MR300, Nippon Polyurethane). Kogyo Co., Ltd.) 5%, hexamethylene diisocyanate trimer having isocyanurate ring (trade name: Coronate EH, Nippon Polyurethane Industry Co., Ltd.) 5%
Were each dissolved.

This hydrophobic liquid was added to a 4% aqueous solution of polyvinyl alcohol (trade name: PVA-117, manufactured by Kuraray Co., Ltd.), and preliminarily stirred with a propeller mixer. The ratio of hydrophobic liquid to polyvinyl alcohol aqueous solution is 100: 150
And Next, this liquid was put into a disperser (trade name: Tornado, manufactured by Asada Iron Works Co., Ltd.) having the structure of FIG. The conditions at this time are: flow rate 10 liters / minute, rotor speed 2000RP
M (peripheral speed 18.8 m / sec), the distance between the rotor blade and the stator blade was 0.5 mm, and the number of passes was once.

The obtained emulsion was measured with a Coulter Multisizer (manufactured by Coulter Co.), and the average particle size was 8.1.
The particle size difference was within ± 20%, and the ratio was 77%. 1 part of diethylenetriamine was added to 100 parts (nonvolatile content) of the emulsified dispersion, heated to 80 ° C. with stirring with a mixer, reacted for 3 hours, and then cooled to room temperature to complete encapsulation.

Microcapsule dispersion liquid thus obtained
80 parts of wheat starch and 15 parts of carboxy-modified styrene-butadiene copolymer latex (solid content) were added to 100 parts (nonvolatile content) to obtain a capsule-containing coating solution prepared to have a solid content concentration of 20%. .. 40 g / m ^{2 of} this coating solution
The above base paper was coated and dried so that the dry weight was 4 g / m ^2, and an upper paper was prepared.

Example 2 The same hydrophobic liquid and hydrophilic liquid as in Example 1 were simultaneously charged into the cylindrical dispersion emulsifier having the structure of FIG. 1 so that the flow rate ratio would be 100: 150. The conditions at this time were as follows: flow rate 5 liter / min, rotation speed 1500 RPM (peripheral speed 14 m / se
c) The blade interval was 0.5 mm, and the number of passes was once.

When the obtained emulsion was measured by Coulter Multisizer, the average particle size was 7.9 μ, and the difference in particle size was ±
The ratio falling within 20% was 72%. Hereinafter, an upper sheet was prepared in the same manner as in Example 1.

Example 3 A 5% aqueous solution (pH 4.5) of an α-methylstyrene-maleic anhydride copolymer and diisopropylnaphthalene in which 5% of crystal violet lactone as a color-developing agent were dissolved were used so that the flow ratio was 150: 100. Then, they were simultaneously charged into a cylindrical dispersion emulsifier having the structure of FIG.

The conditions at this time were: a flow rate of 10 liters / minute, a rotation speed of 2200 RPM (outer peripheral speed of 20.7 m / sec), a gap between the rotor blade and the stator blade of 0.3 mm, and the number of passes was 1.
It was time. When the obtained emulsion was measured with a Coulter Multisizer (manufactured by Coulter), the average particle size was 7.3 μ.
The ratio in which the difference in particle size was within ± 20% was 75%.

To this emulsion dispersion was added 50 parts of a 30% aqueous solution of a commercially available melamine-formaldehyde precondensate, and
After reacting at 0 ° C. for 2 hours while continuing stirring, the temperature was lowered to room temperature to prepare a melamine-formaldehyde resin wall membrane capsule. Hereinafter, an upper sheet was prepared in the same manner as in Example 1.

Comparative Example 1 The same preliminary stirring liquid as in Example 1 had one conical rotor and one stator as in FIG. 4 instead of two, and a batch type dispersion emulsifier (not a continuous type). Product name: TK
Using a homomixer manufactured by Tokushu Kika Kogyo Co., Ltd.
The emulsion was batch emulsified until it became 8.1 μ.

The ratio in which the difference in particle size of this emulsion was within ± 20% of 8.1 μ was 56%. Thereafter, the same process as in Example 1 was performed to prepare an upper sheet.

Comparative Example 2 The same preliminary stirring liquid as in Example 1 was averaged using a continuous dispersion emulsifier (product name: TK pipeline homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.) having the structure shown in FIG. Continuous emulsification was carried out in a circulating system until the particle size reached 8.1 μm. That is, while the liquid processed by the dispersion emulsifier according to the arrow in FIG. 4 was circulated through the dispersion emulsifier and fed, a part of the liquid was taken out to emulsify.

The ratio within ± 20% of 8.1 μ is 49
%Met. Thereafter, the same process as in Example 1 was performed to prepare an upper sheet. A performance comparison test was conducted using the thus obtained upper and lower sheets by the method described below, and the results are shown in Table 1.

[Preparation of lower paper] Aluminum hydroxide 65
Parts, 20 parts of zinc oxide, 15 parts of a mixed melt of 3,5-di (α-methylbenzyl) salicylic acid zinc and an α-methylstyrene-styrene copolymer (blending ratio 80/20), polyvinyl alcohol aqueous solution 5 40 g of a coloring agent coating solution prepared by adding 20 parts (solid content) of carboxy-modified styrene-butadiene copolymer latex to a dispersion liquid obtained by pulverizing 100 parts (solid content) and 300 parts of water with a ball mill for 24 hours. / M ²
The base paper was coated and dried so that the dry weight was 5 g / m ^2, and calendered to obtain a lower paper.

(1) Coloring property The upper paper and the lower paper are superposed so that the capsule-coated surface of the upper paper and the developer-coated surface of the lower paper face each other, and 400 kg /
The density of the color image obtained by applying a load of cm ² was measured with a Macbeth densitometer (trade name: RD-914 type, filter visual). The higher the value, the higher the concentration.

(2) Corrosion resistance In the same manner as in the color development test, the upper paper and the lower paper are superposed and 1
After applying a load of kg / cm ² for 10 times, the degree of color stain on the surface coated with the color developer was judged. ○: Almost no dirt △: Very dirty ×: Very dirty

[0048]

[Table 1]

[0049]

As is clear from the results shown in Table 1, the microcapsules obtained by the method of the present invention provided excellent pressure-sensitive copying sheets which were excellent in color development and were less likely to cause color stain.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a disperser used in the present invention.

FIG. 2 is an explanatory diagram with a rotor removed in order to explain the configuration of an example of a disperser used in the present invention. This is an example in which protruding blades are provided on the entire outer wall of the rotor and the inner wall of the stator, but the blades are partially omitted.

FIG. 3 is a partial sectional view of a stator and a rotor in the axial direction.

FIG. 4 shows an example of a conventional continuous emulsifier.

[Explanation of symbols]

 1 rotor 2 holes 3 stator 4 stator 5 rotor 6 cooling jacket

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimei Takatani 4-3-1, Jokoji Temple, Amagasaki City, Hyogo Prefecture Kanzaki Paper Mill Kanzaki Mill

Claims (5)

[Claims] 1. A stator having a cylindrical shape, a stator having a protruding blade on an inner wall thereof, and a cylindrical rotor having an inner wall and having a protruding blade on an outer wall thereof, wherein the stator and the rotor are rotated by rotating the rotor. Method for producing microcapsules in which a hydrophobic liquid is emulsified and dispersed in a hydrophilic liquid by a disperser that applies a shearing force to a liquid passing through the space, and a wall film encapsulating the emulsified and dispersed hydrophobic droplets is formed. .. 2. The stator inner wall and the rotor outer wall have protruding blades each having a truncated pyramid shape, and the interval between the protruding portion of the stator inner wall blade and the recessed portion of the rotor outer wall blade and the protruding blade of the rotor outer wall. Of the blade and the concave portion of the blade on the inner wall of the stator are 0.1 to 1.0 mm, and the outer circumference of the rotor is 10 mm.
The method for producing a microcapsule according to claim 1, wherein the microcapsule is rotated at a speed of -25 m / sec. 3. The shaft of the stator is installed substantially vertically, and a hydrophobic liquid and a hydrophilic liquid are sent from the lower part of the stator, and shearing occurs while the liquid moves upward in the interval between the stator and the rotor. The method for producing microcapsules according to claim 1, wherein the microcapsules are emulsified and dispersed by receiving a force. 4. The method for producing microcapsules according to claim 1, wherein the stator has a jacket structure that allows a refrigerant to pass therethrough, and emulsion dispersion is performed while cooling the inside of the disperser. 5. The method for producing microcapsules according to claim 1, wherein the hydrophobic liquid contains a color former and the microcapsules are for pressure-sensitive copying sheets.