JPH10249185A - Production of microcapsule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for easily producing microcapsules having uniform grain sizes of a narrow grain size distribution. SOLUTION: The device installed with a stator 3 having a cylindrical part provided with plural pieces of through-holes along a circumferential direction and rotor 8 having the cylindrical part provided with plural pieces of through- holes along the circumferential direction in such a manner that the cylindrical part 12 of the stator 3 and the cylindrical part 10 of the rotor 8 have a specified spacing necessary for generating a shearing effect and exist concentrically is used. The rotor 8 is concentrically rotated relative to the stator 3 by fixing the stator 3 and the liquid to be treated which consists of a hydrophobic liquid and a hydrophilic liquid is supplied from the central direction of the cylindrical part 10 of the rotor 8. The liquid is passed through the through-holes of the cylindrical part 12 of the stator 3 and the through-hole of the cylindrical part of the rotor and is discharged outside the cylindrical parts, by which the emulsion emulsified and dispersed with the hydrophobic liquid in the hydrophilic liquid is formed. The capsule wall films enclosing the emulsified and dispersed hydrophobic liquid are then 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 containing a hydrophobic substance, and more particularly, to a method for producing microcapsules having a narrow particle size distribution and a uniform particle size.

[0002]

2. Description of the Related Art Microcapsules are suitable for stably retaining substances having chemical reactivity, unstable substances, liquid substances, etc., and are used for pressure-sensitive copying paper, pharmaceuticals, adhesives, dye capsules and the like. It is used for various purposes.

Generally, in microcapsules, the uniformity of the particle size of the capsule is an important factor in quality. For example, in pressure-sensitive copying paper, microcapsules containing a colorless coloring agent that forms a color when it comes into contact with a developer are usually present on the back surface of the copying paper, but the particle diameter of the microcapsules is not uniform. When a capsule having a large particle size is present, the capsule is easily broken due to friction during storage and handling, which causes color stain. On the other hand, if there is a capsule extremely smaller than the average particle size, there is a problem that the coloring property at the time of recording deteriorates because the capsule is hard to be broken.

[0004] Usually, microcapsules are manufactured by mixing and emulsifying a hydrophobic liquid in a hydrophilic liquid to form an emulsion, and then forming a wall film to obtain microcapsules having a uniform particle size. Therefore, it is important to obtain an emulsion having a uniform particle size. In the production of microcapsules, as a method of obtaining an emulsion having a uniform particle size, a method of adding a water-soluble solvent to improve the uniformity of the emulsion (JP-A-56-147627), For improving the uniformity of an emulsion by using an emulsifier (JP-A-58-401)
42, JP-A-58-202034 and the like.

In each of these methods, an emulsifier is an emulsifier / disperser called a homomixer. This emulsifying and dispersing machine will be described based on a schematic diagram of an example of a homomixer shown in FIG. This device basically consists of a high-speed rotating rotor 17 having 4 to 5 blades,
It is composed of a stator 19 having a substantially conical recess matching the rotor 17 and having several discharge holes 18 opposed to the blades, and a rectifying plate 20. The rotor 17 is rotated at a high speed via a shaft 21. The dispersion liquid is sucked from the lower portion of the stator 19 by utilizing the suction effect generated by this rotation, and a shear force is generated in the gap portion 22 between the blades of the rotor 17 and the stator 19 to emulsify and disperse.
The emulsion is discharged upward from the discharge hole 18 of the stator, and this rising flow is changed by the upper straightening plate 20 and is lowered along the side of the tank to return to the bottom of the container again. There are two types of emulsification methods using such a homomixer. One method is called a batch method, in which a rotor and a stator are set in a tank, and the mixture in the tank is kept constant by the rotor and the stator. This is a method of emulsifying by dispersing over time, and in order to promote the circulation of the liquid, the same angle and twist as the blades inside the spiral pump are applied to the stator to perform circulation and dispersion. On the other hand, the continuous type is a method in which the rotor and the stator are not put in the liquid in the tank, but put in another cylindrical container, and the mixed liquid is introduced into the emulsifying and dispersing machine through a pipe to perform the emulsifying dispersion. is there. In this case, it is common practice to put several sets of rotors and stators in a cylinder in order to increase the dispersion efficiency, and to provide a circulation line in order to increase the number of shears. further,
Like the batch type, add a spiral pump blade-like twist,
Increase the number of shears.

However, in these emulsification methods using a homomixer, even though the action of a uniform shearing force is limited to a very limited range near the rotor and the stator, circulation of the dispersion liquid to this portion is performed. When the number of dispersions in the entire dispersion is non-uniform, coarse particles are present in portions where the number of shears in the dispersion is low, and particles with a very small particle size are generated in portions where the number of shears is high in the dispersion. Only an emulsion having a wide distribution and a particle size distribution in a wide range of several% to several hundred% with respect to a target particle size can be obtained.
As a result, the obtained microcapsules also have a broad particle size distribution, which is not satisfactory in terms of particle size uniformity.

[0007]

SUMMARY OF THE INVENTION The main object of the present invention is to:
An object of the present invention is to provide a method for easily and stably producing uniform microcapsules having a narrow particle size distribution and a small particle size.

[0008]

The inventor of the present invention has conducted intensive studies in view of the problems of the prior art as described above. A stator having a cylindrical portion provided with a plurality of through holes along the rotor and a rotor having a cylindrical portion provided with a plurality of through holes along the circumferential direction are required for the cylindrical portions to generate a shearing action. A method for producing an emulsion by emulsifying and dispersing a liquid to be treated consisting of a hydrophobic liquid and a hydrophilic liquid by rotating a rotor at a high speed by using an apparatus which is arranged so as to be concentric and located at intervals. According to the action of high-speed shear force or ultrasonic waves, the liquid to be treated is sheared,
By receiving the action of crushing and mixing continuously, a uniform emulsified dispersion having a narrow particle size distribution can be obtained in a short time, and then, by forming a capsule wall film on the emulsified hydrophobic liquid, a uniform emulsified dispersion can be obtained. The present inventors have found that microcapsules having a large particle size can be obtained in a short time by a simple method, and have completed the present invention.

That is, the present invention provides a stator having a cylindrical portion provided with a plurality of through holes along the circumferential direction, and a rotor having a cylindrical portion provided with a plurality of through holes along the circumferential direction. ,
Using a device in which the cylindrical portion of the stator and the cylindrical portion of the rotor have a constant interval necessary for generating a shearing action and are installed concentrically, fixing the stator, and fixing the rotor to the stator By rotating concentrically, a liquid to be treated consisting of a hydrophobic liquid and a hydrophilic liquid is supplied from the center of the cylindrical portion of the rotor, and is passed through the through-hole of the cylindrical portion of the stator and the through-hole of the cylindrical portion of the rotor. A microcapsule characterized by forming an emulsion in which the hydrophobic liquid is emulsified and dispersed in the hydrophilic liquid by discharging to the outside of the part, and then forming a capsule wall film enclosing the emulsified hydrophobic liquid. Related to a manufacturing method.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a method for emulsifying and dispersing a liquid to be treated comprising a hydrophobic liquid and a hydrophilic liquid,
A stator having a cylindrical portion provided with a plurality of through holes along the circumferential direction, and a rotor having a cylindrical portion provided with a plurality of through holes along the circumferential direction, a cylindrical portion of the stator and a cylindrical portion of the rotor. Using a device installed so that the portions have a necessary interval for generating a shearing action and are positioned concentrically, the stator is fixed, the rotor is concentrically rotated with respect to the stator, and the liquid to be treated is Is supplied from the center of the cylindrical portion of the rotor, passes through the through-hole of the cylindrical portion of the stator and the through-hole of the cylindrical portion of the rotor, and is discharged to the outside of the cylindrical portion. It is necessary to adopt a method of preparing an emulsion emulsified and dispersed in water.

FIG. 1 is a longitudinal sectional view of an example of an emulsifying and dispersing machine used in this emulsifying and dispersing method, and FIG. 2 is a front view of a rotor thereof.

In this emulsifying and dispersing machine, reference numeral 1 denotes a casing, and a stator 3 is fixed by a suction cover 2. The suction cover 2 is provided with a suction port 4, and the casing 1 is provided with a discharge port 5. A main shaft 7 is rotatably provided through a shaft sealing device 6 provided in the casing 1, and a rotor 8 is fixed to a tip of the main shaft 7 by a nut 9.

The rotor 8 has a cylindrical portion 10 having a shroud 1
The cylindrical portion 10 is provided with a plurality of through holes 14 along the circumferential direction. The stator 3 is provided with two cylindrical portions 12 and 13 so as to sandwich the cylindrical portion 10 of the rotor concentrically from both sides at an interval of S ₁ and S ₂ in the radial direction. Also, a plurality of through holes (not shown) are provided along the circumferential direction. The interval S ₁ between the rotor cylindrical portion 10 and the stator cylindrical portion 12 and the interval S ₂ between the rotor cylindrical portion 10 and the stator cylindrical portion 13 are changed by the rotation of the rotor 8, the gap between the rotor cylindrical portion 10 and the stator cylindrical portion 12, And rotor cylinder 1
It is set appropriately within a range where a shearing action occurs in the liquid to be processed in each of the gaps between the stator cylinder portion 13 and the zero.

The shape of the through holes of the rotor and the stator is not particularly limited, and for example, a slit shape, a circular shape, an elliptical shape,
Any shape such as a star or a rhombus can be used. The shape and number of the through holes may be the same or different between the rotor and the stator. Also, the through holes may be at equal intervals or at irregular intervals. By appropriately selecting the number, spacing, and the like of the through holes, a shearing action does not occur at one time, and vibration and noise can be prevented. The emulsifying and dispersing apparatus shown in FIG.
0 and stator cylindrical portions 12, 13 are provided with slit-shaped through holes, and both the rotor cylindrical portion 10 and the stator cylindrical portions 12, 13 have a comb-shaped ring shape.

When a slit-shaped through hole 14 is provided in the cylindrical portion 10 of the rotor 8, the through hole 14 is selected to have an appropriate length. This through hole 14 is not limited to be parallel, and one or both may be inclined with respect to the radial direction. The ends 15, 16 are preferably sharp.

In such an emulsifying and dispersing machine, when the rotor 8 is rotated by driving the main shaft 7, the liquid to be treated is sucked from the suction port 4 by the pump action of the rotor 8, and the through-hole of the stator cylindrical portion 12 and the rotor cylindrical portion 10 Through hole 14, stator cylindrical portion 13
Through the through hole, and is discharged from the discharge port 5.

According to such a method, the liquid to be treated generates a swirling flow in each gap between the cylindrical portions 12 and 13 of the stator 3 and the cylindrical portion 10 of the rotor 8, and a uniform high-speed shearing force is generated. In addition, centrifugal flow occurs in the radial direction in the through holes of the rotor and the stator, and the radial flow continuously repeats collision with the swirling flow. Further, when the rotor 8 provided with the through holes rotates at high speed, a high frequency is generated, and effects such as crushing and dispersion can be obtained. Due to these actions, the liquid to be treated is continuously subjected to actions such as shearing, crushing, and mixing, so that a uniform emulsified dispersion having a narrow particle size distribution can be obtained in a short time.

In the emulsifying and dispersing machine shown in FIG. 1, the stator 3 is provided with two cylindrical portions 12 and 13 so as to sandwich the cylindrical portion 10 of the rotor 8 concentrically from both sides. May be provided at only one cylindrical portion. In this case, either the cylindrical portion of the stator 3 or the cylindrical portion of the rotor 8 may be on the outside. Further, the rotor 8 may be provided with two or more cylindrical portions, and the stator 3 may be provided with three or more cylindrical portions.

The emulsifying and dispersing machine shown in FIG. 1 has one set of a combination of a stator and a rotor. In the present invention, an emulsifying and dispersing machine having two or more sets of a combination of a stator and a rotor can be used. .

FIG. 3 is a longitudinal sectional view of an example of an emulsifying and dispersing machine having three sets of a stator and a rotor.

In the dispersing machine shown in FIG. 3, when the rotor 8 rotates, the liquid to be treated is sucked through the suction port 4, and the through hole of the cylindrical portion 12 of the first stage stator 3, the through hole of the cylindrical portion 10 of the rotor 8,
It flows out through the through hole of the cylindrical portion 13 of the stator 3,
Then, the to-be-processed liquid is rotated by the second-stage rotor 8 ′, whereby the through-hole of the cylindrical portion 12 ′ of the second-stage stator 3 ′, the through-hole of the cylindrical portion 10 ′ of the rotor 8 ′, and the stator cylindrical portion 13 are formed. '
The liquid to be treated flows out through the through hole of the third stage, and the liquid to be processed is further rotated by the rotation of the third stage rotor 8 ″. Cylindrical part 10 "
Through the through hole of the cylindrical portion 13 ″ of the stator 3 ″, and is discharged from the discharge port 5.

When an emulsifying and dispersing machine having such a combination of two or more sets of stators and rotors is used, a shearing action is exerted on the combination of each stator and rotor, so that the particle size distribution is narrowed in a shorter time. A uniform emulsified dispersion can be obtained.

The operating conditions of the emulsifying and dispersing machine when emulsifying and dispersing into an emulsion are as follows: the diameters of the cylindrical portions of the rotor and the stator in the emulsifying and dispersing machine; The flow rate of the liquid to be treated, the number of revolutions of the rotor, and the like may be set as appropriate so that a uniform emulsified dispersion can be obtained in a short time, although it is not uniform because it can vary depending on the type of the treatment liquid. If necessary, the emulsion discharged from the emulsifying and dispersing machine can be supplied again to the emulsifying and dispersing machine to repeatedly emulsify and disperse the emulsion. The particle size of the dispersed particles in the emulsion can be easily controlled by changing the number of revolutions of the rotor and the like.

In the present invention, the mixed liquid of the hydrophobic liquid and the hydrophilic liquid used as the liquid to be treated is prepared by previously mixing the hydrophobic liquid and the hydrophilic liquid and preliminarily emulsifying and dispersing the hydrophobic liquid in the hydrophilic liquid. It can be supplied to the emulsifying and dispersing machine in a state, or the hydrophobic liquid and the hydrophilic liquid can be separately added to the emulsifying and dispersing machine.

In the present invention, the hydrophobic liquid serves as a core substance of the microcapsules, and various kinds of components included in the microcapsules according to the purpose of use are necessary for forming the capsule wall film, if necessary. What added components etc. can be used.

For example, when used as a microcapsule for pressure-sensitive copying paper, the hydrophobic liquid serving as the core substance of the microcapsule is further employed in a solution in which an electron-donating organic color former is dissolved in oil. What added the necessary wall membrane component according to the microencapsulation method can be used. As the oil, natural or synthetic oils can be used alone or in combination, and examples thereof include cottonseed oil,
Examples thereof include kerosene, paraffin, naphthenic oil, alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diarylalkane, and dibasic acid esters such as phthalate. As the electron-donating organic color former, known materials corresponding to a desired color tone can be used.
Bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl)
Triallylmethane compounds such as -3- (1,2-dimethylindol-3-yl) phthalide; 4,4'-bis-
Dimethylaminobenzhydryl benzyl ether, N-
Diphenylmethane compounds such as halophenyl-leuco auramine and N-2,4,5-trichlorophenyl leuco auramine; 7-dimethylamino-3-chlorofluoran, 7-dimethylamino-3-chloro-2-methylfluoran , 2-phenylamino-3-methyl-6- (N-
Fluorane compounds such as ethyl-Np-tolylaminofluoran; thiazine compounds such as benzoylleucomethylene blue and p-nitrobenzylleucomethylene blue; 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3- Spiro compounds such as propyl-spiro-dinaphthopyran and 3-propyl-spiro-dibenzopyran are exemplified.

As the hydrophilic liquid, an aqueous solution obtained by dissolving a surfactant, a protective colloid, components necessary for forming a capsule wall film, and the like, as necessary, is usually used.

There is no particular limitation on the mixing ratio of the hydrophobic liquid and the hydrophilic liquid, and depending on the type of the component used,
It may be used in such a ratio that a stable oil-in-water emulsion can be obtained. Usually, the weight ratio of the hydrophobic liquid to the hydrophilic liquid is used in the range of the former: the latter = about 10:90 to 60:40.

After producing an emulsion having a uniform particle size by the above-described method, a microcapsule can be obtained by forming a capsule wall film at the interface between the emulsified and dispersed hydrophobic liquid and the hydrophilic liquid.

As a method for forming the capsule wall film, various conventionally known methods, for example, a coacervation method, an in situ method, an interfacial polymerization method and the like can be applied. The conditions for forming the capsule wall film may be in accordance with a known method. In these cases, depending on the encapsulation method employed,
The necessary components may be previously present in the hydrophobic liquid and / or the hydrophilic liquid.

For example, in the coacervation method, typically, an emulsion is formed by using an aqueous solution containing gelatin, and gum arabic, sodium alginate, styrene-maleic anhydride copolymer, vinyl methyl ether The capsule wall film can be formed by adding an anionic substance such as a maleic anhydride copolymer, a phthalic ester of starch, or polyacrylic acid, and adjusting the concentration, pH, and the like.

In the in-situ method, a monomer, a low polymer or a condensate, which becomes a wall film, is supplied together with a polymerization catalyst from only one of the inside and outside of the core material dispersed in a dispersion medium, and the polymerization or condensation reaction is performed on the surface of the core material. A typical wall film is a melamine-formalin resin or the like. Melamine-formalin resin capsules are obtained by obtaining an emulsified dispersion, adding a partially condensed aqueous solution of melamine-formalin prepolymer, adjusting the pH, raising the temperature, and precipitating and hardening the resin around the hydrophobic liquid. Then, it can be obtained by forming a capsule wall film. In addition, as a method of forming a melamine-formalin resin capsule from the hydrophobic liquid by an in-situ method, a melamine-formalin prepolymer is dissolved in a hydrophobic liquid, and emulsified and dispersed in a hydrophilic liquid. There is a method of forming a capsule wall film by precipitating a resin around and curing the resin.

The interfacial polymerization method is a method of forming a wall film of polyamide, epoxy resin, polyurethane, polyurea or the like at an interface between a hydrophobic liquid and a hydrophilic liquid, and a hydrophilic film of polyamine, glycol, polyhydric phenol or the like. A capsule wall film is formed by dissolving a monomer and hydrophobic monomers such as polybasic acid halide, bishaloforme, and polyisocyanate in a hydrophilic liquid and a hydrophobic liquid, respectively, and causing a polymerization reaction at the interface. it can. In the present invention, this method is preferable, and it is particularly preferable to use an aromatic polyvalent isocyanate and an aliphatic polyvalent isocyanate in combination as the hydrophobic monomer. In this case, the mixing ratio of both is as follows: aromatic polyisocyanate: aliphatic polyisocyanate (weight ratio) = 1: 0.
About 01 to 100 is preferable, and about 1: 0.1 to 10 is more preferable. In this way, by using the aromatic polyvalent isocyanate and the aliphatic polyvalent isocyanate together, the particle size distribution is uniform, and the coloring property is improved. , Microcapsules excellent in friction resistance, pressure resistance and the like can be obtained.

According to the method of the present invention, when a hydrophobic liquid to which a component for forming a wall film is added by an interfacial polymerization method or an in-situ method is used, the particle size of the capsule is particularly reduced by an emulsification method using a conventional homomixer. The microcapsules which tend to be non-uniform and the strength of the formed microcapsules tend to be low can easily form microcapsules having a uniform particle size and appropriate strength. Although the reason is not clear, in the emulsification method using a homomixer, heat is generated at the time of emulsification and a part of the monomer component in the hydrophobic liquid reacts, so that a thin film is formed on the surface and it is difficult to obtain a uniform particle size,
In addition, this thin film may be destroyed during emulsification, so that the strength of the wall film may be reduced when the capsule wall film is formed. It is presumed that the emulsification time was short because the average particle size was obtained, and it was difficult to form a thin film due to the reaction of the monomer components in the hydrophobic liquid.

[0035]

According to the method of the present invention, a liquid to be treated comprising a hydrophobic liquid and a hydrophilic liquid can be easily converted into an emulsion having a narrow particle size distribution and a uniform particle diameter in a short time. Further, the particle diameter can be easily controlled by changing the rotation speed of the rotor, and adjustment to the target particle diameter is easy. Then, by forming a capsule wall film containing the emulsified and dispersed hydrophobic liquid, the obtained microcapsules have a uniform particle size with a narrow particle size distribution.

The microcapsules thus obtained can be effectively used in various fields where microcapsules are conventionally used, such as pressure-sensitive copying paper, pharmaceuticals, adhesives, and dye capsules. For example, in pressure-sensitive copying paper using microcapsules containing an electron-donating organic color former, some of the microcapsules are destroyed during storage or handling because the uniformity of the particle size of the microcapsules is good. As a result, it is possible to reduce the amount of microcapsules to be used because it is unlikely to cause coloring stains and uniform coloring is achieved.

[0037]

The present invention will be described in more detail with reference to the following examples, but it should not be construed that the invention is limited thereto. Unless otherwise specified, parts and% in the examples indicate parts by weight and% by weight, respectively.

Example 1 Crystal violet lactone (5%) was used as an electron-donating organic color former in diisopropyl naphthalene (KMC-113, manufactured by Kureha Chemical Co., Ltd.), and polymethylene poly (aromatic polyisocyanate) was used as a microcapsule wall film material. Phenyl isocyanate (Millionate MR300,
5% of a trimer of hexamethylene diisocyanate having an isocyanurate ring which is an aliphatic polyvalent isocyanate (Coronate EH, manufactured by Nippon Polyurethane Industry Co., Ltd.) was dissolved in 5%.

This hydrophobic liquid was added to a 4% aqueous solution of polyvinyl alcohol (PVA-117, manufactured by Kuraray),
Preliminary stirring was performed with a propeller mixer. The weight ratio between the hydrophobic liquid and the aqueous polyvinyl alcohol solution was 100: 100.

Next, using a continuous emulsifying and dispersing machine (Ebara Milder, manufactured by Ebara Corporation) having a combination of three sets of rotors and stators as shown in FIG. / Min, and the mixture was stirred at a rotor rotation speed of 6,000 rpm / min to obtain an emulsion from the outlet.

The particle size distribution of the obtained emulsion was measured with a commercially available particle size measuring device (Coulter Multisizer, manufactured by Coulter Co.). The average particle size was 7.0 μm, and the particle size difference was within ± 20%. Was 70%, which was excellent in uniformity.

To 100 parts of this emulsion (non-volatile content), 1 part of diethylenetriamine, which is a polyvalent amine, was added, heated to 80 ° C. while stirring with a mixer, and reacted for 3 hours by an interfacial polymerization method. A capsule wall film was formed to produce a microcapsule.

The obtained microcapsules had almost the same average particle size and particle size distribution as those of the above emulsion, and had good uniformity.

Comparative Example 1 The same premixed liquid as in Example 1 was used by using a continuous emulsifying and dispersing machine (TK pipeline homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.) having a rotor and a stator shown in FIG. The mixture was continuously emulsified in a circulation system until the average particle size became 7.0 μm. The ratio of the obtained emulsion within 43% of the particle size difference within ± 20% of 7.0 μm was poor in uniformity.

Using this emulsion, microcapsules were prepared in the same manner as in Example 1. The average particle size and particle size distribution of the obtained microcapsules were almost the same as those of the emulsion used, and were uniform. It was inferior in sex.

Example 2 Using the same emulsifying and dispersing machine as in Example 1, the flow rate was 400 g /
Except that the rotation speed was 8,000 rpm / min.
An emulsion was obtained in the same manner as in Example 1.

The particle size distribution of the obtained emulsion was measured with a Coulter Multisizer (manufactured by Coulter Inc.). The average particle size was 6.7 μm, and the ratio of the particle size difference within ± 20% was 71%. And uniformity were good.

Using the emulsion, a capsule wall film was formed in the same manner as in Example 1 to obtain microcapsules. The obtained microcapsules had almost the same average particle size and particle size distribution as the emulsion used, and had good uniformity.

Comparative Example 2 The same premixed liquid as in Example 1 was used using a continuous emulsifying and dispersing machine (TK pipeline homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.) having a rotor and a stator as shown in FIG. The emulsion was continuously emulsified in a circulation system until the average particle size became 6.7 μm. The ratio of the obtained emulsion within 42% of the particle size difference falling within ± 20% of 6.7 μm was poor in uniformity.

Using this emulsion, microcapsules were prepared in the same manner as in Example 1. The average particle size and particle size distribution of the obtained microcapsules were almost the same as those of the emulsion used, and were uniform. It was inferior in sex.

Example 3 Using the same emulsifying and dispersing machine as in Example 1, the flow rate was 600 g /
An emulsion was obtained in the same manner as in Example 1, except that the rotation speed was 10,000 rpm / min.

The particle size distribution of the obtained emulsion was measured with a Coulter Multisizer (manufactured by Coulter Inc.). The average particle size was 6.4 μm, and the ratio of the particle size difference within ± 20% was 68%. And uniformity were good.

Using this emulsion, a capsule wall film was formed in the same manner as in Example 1 to obtain microcapsules. The obtained microcapsules had almost the same average particle size and particle size distribution as the emulsion used, and had good uniformity.

Comparative Example 3 The same premixed liquid as in Example 1 was used using a continuous emulsifying and dispersing machine (TK pipeline homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.) having a rotor and a stator as shown in FIG. The emulsion was continuously emulsified in a circulation system until the average particle size became 6.4 μm. The ratio of the obtained emulsion within 40% of the particle size difference falling within ± 20% of 6.4 μm was poor in uniformity.

Using this emulsion, microcapsules were prepared in the same manner as in Example 1. The average particle size and particle size distribution of the obtained microcapsules were almost the same as those of the emulsion used, and were uniform. It was inferior in sex.

Example 4 Using the same emulsifying and dispersing machine as in Example 1, the flow rate was 100 g /
Except that the rotation speed was set to 4,000 rpm / min.
An emulsion was obtained in the same manner as in Example 1.

The particle size distribution of the obtained emulsion was measured using a Coulter Multisizer (manufactured by Coulter Inc.). The average particle size was 7.4 μm, and the ratio of the particle size difference within ± 20% was 65%. And uniformity were good.

Using the emulsion, a capsule wall film was formed in the same manner as in Example 1 to obtain microcapsules. The obtained microcapsules had almost the same average particle size and particle size distribution as the emulsion used, and had good uniformity.

Comparative Example 4 The same premixed liquid as in Example 1 was used using a continuous emulsifying and dispersing machine (TK pipeline homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.) having a rotor and a stator shown in FIG. The mixture was continuously emulsified in a circulation system until the average particle size became 7.4 μm. The ratio of the obtained emulsion within 45% of the particle size difference falling within ± 20% of 7.4 μm was poor in uniformity.

Using this emulsion, microcapsules were prepared in the same manner as in Example 1. The average particle size and particle size distribution of the obtained microcapsules were almost the same as those of the emulsion used, and were uniform. It was inferior in sex.

Test Example Using the microcapsules containing the color formers obtained in Examples and Comparative Examples, pressure-sensitive copying paper was prepared by the following method.
A performance test was performed.

[Preparation of Microcapsule Coating Liquid] 70 parts of wheat starch granules and 15 parts of carboxy-modified styrene-butadiene copolymer latex (solids) were added to 100 parts (solid content) of the microcapsule dispersion obtained in Examples or Comparative Examples. ), And the solid content was adjusted to 20% to obtain a microcapsule coating liquid.

[Preparation of developer coating solution] Calcium carbonate 6
5 parts, zinc oxide 20 parts, 3,5-di (α-methylbenzyl) salicylic acid zinc salt 15 parts, 3% polyvinyl alcohol (N-300, manufactured by Nippon Synthetic Chemical Industry) aqueous solution 15
To a dispersion obtained by pulverizing 0 parts and 100 parts of water with a ball mill for 24 hours, 20 parts (solid content) of a carboxy-modified styrene-butadiene copolymer latex was added.
It was adjusted to 5% to obtain a developer coating solution.

[Production of Upper Paper] The above-mentioned microcapsule coating liquid was applied to the surface of a high-quality paper having a basis weight of 40 g / m ^{2 using} an air knife coater so that the coating amount after drying was 4 g / m ² and dried. Thus, an upper paper for pressure-sensitive copying paper was produced.

[Manufacture of lower paper] The above developer coating solution was applied onto the surface of a high-quality paper having a basis weight of 40 g / m ² , and the coated amount after drying was 5 g.
/ M ² with an air knife coater and dried to produce a lower sheet for pressure-sensitive copying paper.

[Test Method] Using the above-mentioned upper paper and lower paper, a performance test was performed by the following method. The results are shown in Table 1 below.

(1) Color-forming property The upper paper and the lower paper are overlapped so that the coating surfaces face each other, and the paper is passed through a super calender to form a color. After one hour, the color density of the developer-coated surface is determined by a Macbeth reflection type. Densitometer RD
It was measured with Model 914 (Macbeth).

(2) Pressure resistance The upper paper and the lower paper are overlapped so that the coating surfaces face each other, and they are sandwiched from above and below by 50 sheets of high quality paper, and a load of 20 kg / cm ² is applied to an area of 3 cm square. After one minute,
Visually check the degree of color stain on the surface of the developer application surface,
Evaluation was made according to the following criteria. ◎ Very good with almost no coloring stains. ○ Slight color stains occurred, but no problem in practical use. × Color stains are strong and not practical.

(3) Friction Resistance The upper paper and the lower paper are overlapped so that the coated surfaces face each other, and rubbed five times with a load of 4 kg / cm ² applied thereto, to thereby develop color stains on the developer-coated surface. Was visually checked and evaluated according to the following criteria. ◎ Very good with almost no coloring stains. ○ Slight color stains occurred, but no problem in practical use. × Color stains are strong and not practical.

[0070]

[Table 1]

As is clear from the above results, the microcapsules containing the electron-donating organic color former obtained by the method of the present invention and having good uniformity have good color developability when used for pressure-sensitive copying paper. In addition, coloring stains are less likely to occur during storage and handling.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an emulsifying and dispersing machine.

FIG. 2 is a front view of a rotor of the emulsifying and dispersing machine of FIG.

FIG. 3 is a longitudinal sectional view of a continuous emulsifying and dispersing machine having three sets of a rotor and a stator.

FIG. 4 is a schematic diagram of a homomixer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Casing 2 ... Suction cover 3, 3 ', 3 "... Stator 4 ... Suction port 5 ... Discharge port 6 ... Shaft sealing device 7 ... Main shaft 8, 8', 8" ... Rotor 9 ... Nut 10, 10 ', 10 "
... Cylinder of rotor 11 ... Shroud 12, 12 ', 12 "
... Cylindrical part of stator 13, 13 ', 13 "... Cylindrical part of stator 14 ... Through-hole of rotor 15, 16 ... End part 17 ... Rotor 18 ... Discharge hole 19 ... Stator 20 ... Rectifier plate 21 ... Shaft 22 ... Gap part

Claims (3)

[Claims] 1. A stator having a cylindrical portion provided with a plurality of through holes along a circumferential direction, and a rotor having a cylindrical portion provided with a plurality of through holes along a circumferential direction. The stator is fixed by using a device in which the portion and the cylindrical portion of the rotor have a constant interval necessary for causing a shearing action and are installed concentrically, and the stator is fixed, and the rotor is concentrically mounted on the stator. By rotating, the liquid to be treated consisting of a hydrophobic liquid and a hydrophilic liquid is supplied from the center of the cylindrical portion of the rotor, and is passed through the through-hole of the cylindrical portion of the stator and the through-hole of the cylindrical portion of the rotor. Discharging the emulsion into a hydrophilic liquid to form an emulsion in which the hydrophobic liquid is emulsified and dispersed in the hydrophilic liquid, and then forming a capsule wall film enclosing the emulsified and dispersed hydrophobic liquid. 2. The method according to claim 1, wherein the cylindrical portion of the stator and the cylindrical portion of the rotor are
The manufacturing method according to claim 1, wherein each of the rings is a comb-shaped ring having a slit-shaped through hole. 3. The method according to claim 1, wherein the capsule wall film is formed by an interfacial polymerization method or an in-situ method.