JP2001097818A - Microcapsule and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a microcapsule which is simply and efficiently produced, enables a user to easily control the particle diameter of the microcapsule in a broad range, exhibits fine stability or good feeling on use and release involved oildrops rapidly when applied and to provide a method for producing the microcapsule. SOLUTION: This is a microcapsule 2 which involves oildrops 1 with an average particle diameter of 0.01-3 μm and is obtained by using a hydrophilic polymeric gelatinizer as a capsulation agent and exhibits a capsule fracture strength of 10-500 g/cm2. As the hydrophilic gelatinizer, agar, carrageenan, or the like, is favorable. This microcapsule 2 is obtained by preparing an O/W emulsion from an inner oil phase 1 and a water phase containing the hydrophilic polymeric gelatinizer, dispersioin-emulsifying the above O/W emulsion into an outer oil phase 3 to prepare an O/W emulsion and solidifying the wear phase in the above O/W/O emulsion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcapsule, and more particularly to an improvement in stability, feeling of use, and release of oil droplets contained in a capsule.

[0002]

2. Description of the Related Art Microcapsules having oil droplets encapsulated in capsules have been studied in the fields of foods, pharmaceuticals, cosmetics, and the like. Attempts have been made to improve stability. As a method for producing microcapsules, there is a method in which an O / W emulsion is prepared from an oil phase that becomes oil droplets containing oil and an aqueous phase containing an encapsulating agent, and this emulsion is formed into fine particles and encapsulated. For example, O
/ W emulsion is further dispersed and emulsified in an outer oil phase to form O /
A method of forming a W / O emulsion and encapsulating by curing an aqueous phase, spray cooling in which the O / W emulsion is cured while spraying it in air, and curing in a gas or liquid by dropping the O / W emulsion from a nozzle Dropping method.

[0003]

However, it is difficult to reduce the emulsified particles of the O / W emulsion to 1 μm or less by the ordinary emulsification method. For example, an O / W emulsion having an emulsified particle diameter of 1 μm or less was obtained. However, since the stability is not sufficient, the oil droplets tend to fuse with each other in the subsequent process, and the diameter of the oil droplets included in the microcapsules tends to increase. In such a case, there is a problem that the diameter of the microcapsules must be increased in order to increase the encapsulation efficiency of the encapsulated oil droplets.

[0004] In particular, in the method via the O / W / O emulsion, the O / W emulsion is further dispersed and emulsified in the outer oil phase. Coalescence is likely to occur. For this reason, the temperature and stirring speed during O / W / O emulsification are limited, and it is very difficult to control the particle size of the microcapsules, and the obtained capsules have insufficient stability. It has also been desired to suppress loss of the inner oil phase during production.

[0005] Further, stability of the microcapsules when blended with other bases, feeling on use on the skin, and releasability of encapsulated oil droplets are also important. For example, in a product that can be obtained by high-speed stirring in a viscous medium such as an emulsion or cream, when microcapsules are added to the production process, the capsules are easily broken. Capsules are not broken even during the manufacturing process of such products, and when extended and applied on the skin, the capsules are broken without discomfort, oil droplets are rapidly released, and microcapsules with good usability are obtained. Has been very difficult so far.

For example, Japanese Patent Application Laid-Open No. 9-255562 reports an O / W / O emulsion in which a hydrophilic polymer is mixed in an aqueous phase and an organically modified clay mineral is mixed in an outer oil phase.
Even in such a case, when the capsule is taken out of the O / W / O emulsion as a solid content, or is charged as an oily dispersion together with other bases into a product, a machine during the manufacturing process of the product is used. Capsules could be broken by mechanical shearing or changes in base composition.

[0007] The present invention has been made in view of the above-mentioned problems of the prior art. One of the objects of the present invention is to prevent the microcapsules from being broken even when they are added to other bases and commercialized.
The storage stability is good, and when applied, the encapsulated oil droplets are promptly released, and provide a microcapsule with a good feeling in use. One of the reasons is to provide such a microcapsule simply and easily. An object of the present invention is to provide a method for producing microcapsules that can be efficiently produced and that can easily control the capsule particle size in a wide range.

[0008]

DISCLOSURE OF THE INVENTION In view of the above-mentioned problems in the prior art, the present inventors have studied and found that a hydrophilic polymer gelling agent was used so that the breaking strength of the capsule was in a specific range. The present inventors have found that the above problems can be solved in a capsule, and have completed the present invention. That is, the microcapsules according to the present invention have an average particle size of 0.01 to 3 μm.
m, and the encapsulating agent is a hydrophilic polymer gelling agent, and the breaking strength of the capsule is 10 to 500 g /
cm ² .

In the present invention, the main component of the encapsulating agent is preferably a hydrophilic polymer gelling agent which solidifies by heating and cooling, and the hydrophilic polymer gelling agent is agar or carrageenan. Is preferred. In the present invention, the microcapsules preferably contain a hydrophilic nonionic surfactant and a water-soluble solvent. The microcapsule oil dispersion according to the present invention is characterized in that the microcapsules described in any of the above are dispersed in an oil phase.

In the microcapsule oil dispersion of the present invention, an O / W emulsion is prepared from an inner oil phase and an aqueous phase containing a hydrophilic polymer gelling agent. It is preferable to obtain an O / W / O emulsion by dispersing and emulsifying the mixture, and then solidifying the aqueous phase of the O / W / O emulsion. Further, the O / W emulsion is prepared by adding an inner oil phase to a water-soluble solvent containing a hydrophilic nonionic surfactant to prepare an oil-in-water-based emulsion, and adding the oil-in-water-based emulsion to the water-soluble solvent.
O prepared by adding an aqueous solution of a hydrophilic polymer gelling agent
/ W emulsion is preferred.

The microcapsules of the present invention are preferably obtained by removing the outer oil phase of any of the microcapsule oily dispersions described above. Also,
In the microcapsule or the oily dispersion thereof of the present invention, it is preferable that the capsule contains an oily drug. In addition, a cosmetic according to the present invention is characterized by incorporating the microcapsule described in any of the above or an oily dispersion thereof. In addition, a solid cosmetic according to the present invention is characterized by incorporating the microcapsule described above or an oily dispersion thereof.

The method for producing microcapsules according to the present invention comprises the steps of: preparing an internal oil phase and an aqueous phase in which a hydrophilic polymer gelling agent which solidifies by heating and cooling is heated and dissolved in advance.
At a solidification temperature of the gelling agent or higher, the average particle size is 0.01 to 3
an O / W emulsion preparation step of preparing a μm O / W emulsion, an O / W / O emulsion preparation step of dispersing and emulsifying the O / W emulsion in an outer oil phase at or above the solidification temperature of the gelling agent; Cooling the O / W / O emulsion below the solidification temperature of the gelling agent to solidify the aqueous phase, wherein the gel prepared from the aqueous phase has a breaking strength of 10 to 500 g / cm. ² is characterized. In the above-mentioned production method, the O / W emulsion preparation step may comprise adding an internal oil phase component to a water-soluble solvent containing a hydrophilic nonionic surfactant to prepare an oil-in-water solvent emulsion, It is preferable to include a step of mixing the oil-in-solvent-in-aqueous emulsion and an aqueous solution in which a hydrophilic polymer gelling agent that solidifies by heating and cooling is heated and dissolved in advance at a temperature equal to or higher than the solidification temperature of the gelling agent.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The microcapsules of the present invention are prepared by preparing an O / W emulsion from an internal oil phase that becomes oil droplets to be encapsulated and an aqueous phase containing a hydrophilic polymer gelling agent, The emulsion is dispersed and emulsified in a phase to form an O / W / O emulsion.
It can be obtained by solidifying and encapsulating the aqueous phase of the W / O emulsion. FIG. 1 is a conceptual diagram of the microcapsule of the present invention.
It has an encapsulated oil droplet (inner oil phase) 1.

As the hydrophilic polymer gelling agent, those which are usually used in cosmetics, pharmaceuticals and the like, and include those which can be solidified to form a hydrophilic gel. Examples thereof include proteins such as gelatin and collagen, and polysaccharides such as agar, carrageenan, glucomannan, scleroglucan, schizophyllan, gellan gum, alginic acid, curdlan, pectin, hyaluronic acid, and guar gum. Of these, agar, carrageenan, and the like that solidify by heating and cooling to form a gel are preferable in that they are less susceptible to ions and can be easily and uniformly solidified. In the present invention, it is preferable that such a hydrophilic polymer gelling agent that solidifies by heating and cooling be used as a main component of the encapsulating agent. Above all, the properties of the gel,
Agar and carrageenan are preferred from the viewpoint of stability, feeling of use, etc., and agar is particularly preferred. As agar, for example, Ina agar PS-84, Z-10, AX-30, AX
Commercial products such as -100, AX-200, T-1, S-5, and M-7 (manufactured by Ina Food Industry Co., Ltd.) can be used. In the present invention, two or more hydrophilic polymer gelling agents may be used in combination. The present invention relates to a hydrophilic polymer gelling agent that solidifies with ions such as Ca and other coagulants, such as alginic acid, curdlan, and hyaluronic acid, together with a hydrophilic polymer gelling agent that solidifies by heating and cooling. Can be blended in a range that does not impair the effect of the above.

If necessary, other hydrophilic polymers, for example, synthetic polymers such as polyacrylic acid, carboxymethylcellulose, and cationized cellulose, and natural polymers such as xanthan gum and locust bean gum are used in the present invention. Can be blended in a range that does not impair the effect of the above. In particular, when using Celtorol with agar,
Capsules tend to be soft. As the aqueous phase, in addition to water, a component or a drug that can be dissolved or dispersed in water can be added.

As the inner oil phase and the outer oil phase of the present invention, if they are not mixed with the aqueous phase and are entirely liquid at the time of production, they are selected from a wide range of commonly used oils from polar oils to non-polar oils. be able to. For example, hydrocarbon oil, ester oil,
Examples include higher alcohols, higher fatty acids, natural fats and oils, and silicone oils. In addition, components or drugs that can be dissolved or dispersed in these oils can also be blended. In addition, it is preferable that there is a difference in polarity between the inner oil phase and the outer oil phase from the viewpoint of preventing infiltration of the encapsulated oil droplets into the outer oil phase.

In the preparation of the O / W emulsion, which is the first step of the production of the microcapsules of the present invention, the average particle size is 0.01 to 3 μm, preferably 0.01 to 1 μm, which is very fine and stable. It must be an emulsion. If the particle size is too large, it is easy for the subsequent O / W / O emulsification to cause fusion of the inner oil phases and coalescence of the inner oil phase and the outer oil phase, so that sufficient emulsification cannot be performed. Further, the loss of the inner oil phase tends to increase.

As a method for easily obtaining such an O / W emulsion, for example, an emulsification method using a hydrophilic nonionic surfactant and a water-soluble solvent (JP-B-57-29213) is effective. That is, an internal oil phase is added to a water-soluble solvent containing a hydrophilic nonionic surfactant to produce an oil-in-water solvent emulsion, and an aqueous solution of a hydrophilic polymer gelling agent is added to the emulsion. Obtain an O / W emulsion. Regarding the addition of the hydrophilic polymer gelling agent,
Water may be added to the water-in-solvent oil-in-solvent emulsion to form an O / W emulsion, which may then be diluted with a hydrophilic polymer gelling agent aqueous solution. It is also possible to add a hydrophilic polymer gelling agent in a water-soluble solvent in advance as long as no particular problem occurs.

The water-soluble solvent has the effect of dissolving a hydrophilic nonionic surfactant and efficiently orienting it at the interface with the internal oil phase to be added thereafter. Polyhydric alcohols, ketones, aldehydes, ethers, amines, lower fatty acids, and other substances that are hydrophilic and dissolve nonionic surfactants can be selected from a very wide range of substances. Specifically, those described in JP-B-57-29213 are exemplified, but in cosmetics and pharmaceuticals, lower monohydric alcohols such as ethanol and propanol, and 1,3-
It is a lower polyhydric alcohol such as butylene glycol and diethylene glycol. In addition, a small amount of water in a water-soluble solvent,
For example, it may contain 15% by weight or less of water based on the water-soluble solvent.

As the hydrophilic nonionic surfactant, a POE-added type or POE / POP-added nonionic surfactant is preferable. Specifically, Japanese Patent Publication No. 57-29
No. 213 is exemplified. Second stage O /
The W / O emulsion is prepared by dispersing and emulsifying the O / W emulsion in an outer oil phase. The emulsifier used at this time is not particularly limited, and a stirring device usually used for emulsification may be appropriately used. In addition, it is preferable to mix a lipophilic surfactant as an emulsifier in the outer oil phase. As the lipophilic surfactant, any of an ionic surfactant and a nonionic surfactant can be used, and may be appropriately selected from known ones according to the kind of the outer oil phase component and the like.

By solidifying the aqueous phase of such an O / W / O emulsion, a microcapsule containing a large number of fine oil droplets can be obtained. A preferred method for producing the microcapsules of the present invention is to dissolve a hydrophilic polymer gelling agent which solidifies by heating and cooling in water (which may contain other aqueous components as long as there is no problem) beforehand. An aqueous solution is prepared and added to the oil-in-water-soluble emulsion at a temperature higher than the solidification temperature of the gelling agent.
/ W emulsion, a method of preparing an O / W / O emulsion while maintaining the temperature of the system at or above the solidification temperature, and then cooling to a temperature below the solidification temperature to solidify the aqueous phase to form a capsule. For example, in the case of agar or carrageenan, the solidification temperature is about 30 ° C., the preparation temperature of the gelling agent aqueous solution is 90-100 ° C., and the emulsion preparation temperature is about 50-9 ° C.
Preferably, the temperature is 0 ° C. When a material that solidifies by the addition of ions or the like is used together, O / W
After adding a metal salt containing the ion or an aqueous solution thereof to the / O emulsion, it may be cooled.

In the microcapsules of the present invention, the internal oil phase is finely and stably dispersed at the stage of the O / W emulsion as described above, so that the emulsifying conditions for preparing the O / W / O emulsion can be freely set. The capsule diameter can be easily controlled. For example, the temperature at the time of O / W / O emulsification is from room temperature to
The stirring can be performed in a wide range of about 90 ° C. and a stirring speed of about 100 to 10,000 rpm. Even in such a case, there is no loss of the inner oil phase and almost no increase in the oil droplet diameter due to the fusion of the inner oil phase. Absent. The capsule diameter tends to be smaller as the temperature during O / W / O emulsification and the stirring speed are higher, and the capsule diameter is larger as the hydrophilic gelling agent concentration and the viscosity of the outer oil phase are higher. According to the method of the present invention, the microcapsule diameter can be controlled in a wide range of 5 to 1000 μm.

The breaking strength of the microcapsule of the present invention is 1
0 to 500 g / cm ² , preferably 30 to 400 g / c
a m ^2. If the breaking strength is too small, the shear resistance is not sufficient, and if the breaking strength is too large, when applied over the skin, part or all of the capsule remains on the skin without being destroyed, Oil droplets may not be released quickly. Since the breaking strength of the capsule itself cannot be directly measured, in the present invention, the gel prepared with the aqueous phase composition was measured with a rheometer, and this was defined as the breaking strength of the capsule.

In conventional microcapsules, when added to an emulsification step or the like, the capsules may be broken. When compounding microcapsules in an emulsification system, an emulsion is prepared in advance and then slowly stirred. It was necessary to mix microcapsules, and the process was complicated. The microcapsules of the present invention have extremely excellent shear resistance, in which even when added to an emulsification step involving high-speed stirring, capsules hardly break. Therefore, when blended in an emulsified system, the microcapsules can be emulsified after being charged as a solid content or as an oily dispersion together with other components. It can also be blended with various other bases.

Further, in the microcapsules of the present invention, during storage, the oil droplets encapsulated infiltrate into the capsules with time, and the internal oil phase is likely to seep into the external oil phase or the microcapsules are broken. Absent. Therefore, the stability of the drug can be improved by incorporating an oily drug with low stability in the encapsulated oil droplets. Examples thereof include easily oxidizable drugs such as retinol and vitamin E, and easily crystallizable oily drugs such as cyclosporine, vitamin C palmitate, and 4-tert-butyl-4'-methoxybenzoylmethane.

In particular, when a higher fatty acid glyceryl, dextrin fatty acid ester or the like is added to the oil phase as an oily gelling agent during the preparation of the O / W emulsion, the infiltration of the oil droplets contained therein can be remarkably suppressed. The amount of these oily gelling agents is 0.05 to 5% by weight, preferably 0.2 to 1% by weight in the internal oil phase. If the amount is too small, the effect of preventing the oil-based gelling agent from infiltrating is not sufficiently exerted. If the amount is too large, other components may be affected.

The elasticity of the gel is generally softer and more elastic as the Young's modulus is smaller, and harder and less elastic as the Young's modulus is larger. The Young's modulus is applied to the microcapsules of the present invention. It can be used as one of the indices of usability at the time of doing. In the present invention, the microcapsule has a Young's modulus of 30 to 500 N / c.
It is preferably set to m ^2, in particular 30~300N / cm
² , preferably 30 to 200 N / cm ² , provides a smooth feeling of use and release of oil droplets contained therein. The Young's modulus of the capsule was measured with a rheometer on the gel prepared with the aqueous phase composition, similarly to the breaking strength of the capsule,
This was defined as the Young's modulus of the capsule.

The cosmetic containing microcapsules is not particularly limited, and examples thereof include emulsions, creams, lotions,
Basic cosmetics such as serums, massages, scrubs, etc., cleanings such as body soaps, cleansings, foundations, face powders, blushers, lipsticks, eye shadows,
Makeup cosmetics such as eyebrow, mascara, face powder and the like, and hair cosmetics such as hair cream, hair nick, treatment, hair restoration, shampoo, rinse and the like. Examples of the properties include an emulsified state, a solubilized state, a liquid state, a solid state, a gel state, a mousse state, and a spray state. These are not particularly limited as long as the effects of the present invention are not impaired. Further, the cosmetic of the present invention,
Components usually used for cosmetics can be blended.

The microcapsules of the present invention may be mixed with other bases in the form of an oily dispersion or after removing part or all of the outer oil phase 3 by a conventional method such as centrifugation or filtration. You can also. Also, it can be blended with a solid cosmetic such as a foundation or lipstick, or an aqueous base such as a lotion. If the microcapsules of the present invention are left for a long period of time with the solid content remaining, they may shrink. Therefore, it is preferable to stock them in an aqueous base or an oil base. Hereinafter, the present invention will be described with reference to specific examples. In addition, the compounding amount is shown by weight% unless otherwise specified.

Test Example 1 (Microcapsule Formulation) Inner oil phase: Perfume 5% by weight Dioctyl sebacate 15 Aqueous phase: 1,3-butylene glycol 10 POE (60) hydrogenated castor oil 1 Agar See Table 1 Ion-exchanged water to100 Outside Oil phase: POE methyl polysiloxane copolymer 1 octamethylcyclotetrasiloxane 49

(Microcapsule manufacturing method)
It was gradually added to a mixture of 3-butylene glycol and POE (60) hydrogenated castor oil to obtain an oil-in-water-soluble emulsion. Agar was heated and dissolved in ion-exchanged water at 90 ° C to prepare an aqueous agar solution, and cooled to 50 ° C. 50 ℃
The agar aqueous solution was added to the oil-in-water-soluble emulsion heated with stirring while stirring to obtain an O / W emulsion (average particle size: 0.5 μm). The O / W emulsion is added to the outer oil phase and emulsified at 50 ° C. × 500 rpm,
An O / W / O emulsion was prepared. This was gradually cooled to room temperature, and the aqueous phase agar was solidified to obtain a microcapsule oily dispersion (capsule average particle diameter 100 μm).
m, the average particle diameter of the oil droplets included in the mixture is 0.5 μm).

In the present invention, the average particle size of the oil droplets contained in the microcapsules is measured by a dynamic light scattering method (using a dynamic light scattering photometer DLS-700 manufactured by Otsuka Electronics Co., Ltd.). It was determined from the particle size distribution measured with a laser diffraction / scattering type particle size distribution analyzer (manufactured by Horiba, Ltd.).

(Capsule Breaking Strength, Young's Modulus) The aqueous phase was heated and melted at 90 ° C. and cooled to prepare a gel having a thickness of 32 mm. The breaking strength and Young's modulus of this gel were measured with a rheometer (NRM-2010-CW manufactured by Fudo Kogyo Co., Ltd.), and the results were defined as the breaking strength and Young's modulus of the capsule. The measurement conditions are as follows. Range: 200 g test speed: 5 cm / min sweep speed: 5 cm / min adapter diameter: 10 mm when less than the breaking strength 500 g / cm ² breaking strength 500 g / cm ² or more when 3mm detector: 2 kg

(Shear Resistance) The stability (shear resistance) when microcapsules were added to the emulsification step was examined as follows. That is, a W / O cream containing microcapsules was prepared according to the following formulation. W / O emulsification was performed at 70 ° C. × 9000 rpm with a homomixer. The presence or absence of breakage of the microcapsules in the obtained cream was observed with a microscope. If the capsules were broken, the sample was rated as "shear-resistant" x.

Shear resistance test cream: microcrystalline wax 9.0 wt% solid paraffin 2.0 beeswax 3.0 petrolatum 5.0 squalane 34.0 hexadecyl adipate 10.0 propylene glycol 5.0 monooleic acid Glycerin 3.5 POE (20) sorbitan monooleate 1.0 Purified water 22.5 Microcapsule oil dispersion 5.0 Preservatives appropriate amount Perfume appropriate amount

(Release test) Microcapsule oil dispersion and ethanol solution containing 5% fragrance (control)
0.1 g of each was put on the inside of the left and right wrists with a spatula.
Before this was spread with a fingertip (before application) and immediately after being spread (immediately after application), the intensity of odor (perfume odor) with respect to the control was evaluated according to the following criteria. Evaluation criteria ◎: Strength comparable to control. ：: Slightly weaker than control. Δ: Weaker than control. X: Almost no smell.

[0037]

[Table 1]  Sample No. Agar Breaking strength Shear resistance Release testType Blended amount (%) (g / cm ² ) Before application Immediately after application  1 T-1 0.1 5 × × ◎ 2 AX-30 1 30 ○ × ◎ 3 PS-84 0.7 200 ○ × ◎ 4 AX-200 1.5 400 ○ × ◎5 PS-84 1.5 1323 ○ × △

Sample 1 has insufficient shear resistance. Sample 5 had good shear resistance, but the smell immediately after rubbing and spreading the sample on the skin was weaker than that of the control. This is considered to be because the encapsulated oil droplets are not quickly released from the capsule even at the time of application. On the other hand, Samples 2 to 4 hardly smell when placed on the skin, but when rubbed and spread on the skin, smell of the same strength as the control is felt. It was considered that almost all of the encapsulated oil droplets were released from the capsules due to the share. Therefore, in order to exhibit the shear resistance and the quick release property of the encapsulated oil droplets, the breaking strength of the capsule is 10 to 500 g / cm ² , especially 30 to 500 g / cm ² .
Preferably it is 400 g / cm ² .

[0039]

Example 1 As in Test Example 1, a comparison was made between microcapsules prepared by a two-stage emulsification method (Examples) and microcapsules prepared by a conventional method (Comparative Examples). In addition,
In each case, the average particle size of the O / W emulsion was 0.1.
The thickness was 5 μm. The breaking strength of each of the gels prepared in the aqueous phase was 400 g / cm ² . Table 2 shows the results.

[0040]

[Table 2]  Example Example Example Comparative example Comparative example1-1 1-2 1-1 1-2  O / W / O emulsification conditions Temperature (℃) 50 70 50 70Stirring speed (rpm) 500 2,500 500 2,500  Average particle size (μm) Included oil droplet 0.5 0.5 10 Not adjustableCapsule 100 50 500 Not available  Inner oil phase encapsulation rate (%) 100 100 70 −Shear resistance ○ ○ × − 

The oil droplet diameter of the encapsulated oil of the example was almost the same as the particle diameter of the emulsified particle at the time of preparing the O / W emulsion, whereas the oil droplet diameter of the oil of the comparative example was increased to 10 μm. This is because the O / W emulsion was unstable in the comparative example,
It is considered that the coalescence of the internal oil phase occurred significantly during the / O emulsification.

In the examples, the O / W / O emulsification conditions were 50 ° C. × 500 rpm (mild emulsification conditions) and 70 ° C.
× 2500 rpm (severe emulsification conditions) In any case,
The encapsulation efficiency was almost 100% and there was no loss of the internal oil phase. On the other hand, in the comparative example, 50 ° C. × 500 r
Even at pm emulsification conditions, the encapsulation efficiency is low and the internal oil phase loss is significant. Further, when O / W / O emulsification was performed under severe conditions with high temperature or high speed stirring, no O / W / O emulsion was obtained. This suggested that in the comparative example, coalescence of the inner oil phase and the outer oil phase occurred in addition to the fusion of the inner oil phases. Further, the microcapsules of the examples were not broken even when added to the emulsification step and were excellent in shear resistance, but the microcapsules of the comparative examples were frequently broken.
Further, the microcapsule oily dispersion of Example was heated at 50 ° C.
After storage for two months, the encapsulation rate of the inner oil phase was maintained at almost 100%.

As described above, the microcapsules of the present invention can freely set the emulsification conditions in the production thereof,
It is easy to control the particle size of the microcapsules.
It is also understood that the encapsulation rate of the internal oil phase is high and there is no loss during production. The prescription and manufacturing method of the microcapsules in Table 2 and the method for measuring the encapsulation rate of the internal oil phase are as follows.

(Example microcapsules) Internal oil phase: (1) Vitamin A palmitate 5% by weight (2) Cetyl isooctanoate 5 Water phase: (3) POE (60) hydrogenated castor oil 0.5 (4) Glycerin 10 (5) Agar (PS-84) 1 (6) Deionized water 28.5 External oil phase: (7) POE methyl polysiloxane copolymer 0.5 (8) Dimethyl polysiloxane (6 cps) 49.5 Total 100.0

Production method: (1) and (2) were mixed to obtain an internal oil phase. The internal oil phase was gradually added to a mixture of (3), (4) and (6) 0.5% to obtain an oil-in-water-soluble emulsion. (5) was heated and dissolved in 28% of 28% at 90 ° C. to prepare an agar aqueous solution, and cooled to 50 ° C. The aqueous agar solution was added to the oil-in-water-soluble emulsion heated to 50 ° C. while stirring to obtain an O / W emulsion. The O / W emulsion was added to the mixture of (7) and (8) and emulsified while maintaining a predetermined temperature, and the O / W emulsion was added.
A / O emulsion was prepared. This was gradually cooled to room temperature and the aqueous phase agar was solidified to obtain a microcapsule oily dispersion.

(Comparative Example Microcapsules) Internal oil phase: (1) stearic acid 2% by weight (2) squalane 10 aqueous phase: (3) sorbitan monooleate 2 (4) glycerin 5 (5) agar (PS- 84) 1 (6) Deionized water 30 External oil phase: (7) POE methyl polysiloxane copolymer 0.5 (8) Dimethyl polysiloxane (6 cps) 49.5 Total 100.0

Production method: (1) and (2) were mixed to form an internal oil phase. The internal oil phase was added to a 13% mixture of (3), (4) and (6) and emulsified to obtain an O / W emulsion.
(5) was heated and dissolved in 17% of 17% at 90 ° C. to prepare an agar aqueous solution, and cooled to 50 ° C. The agar aqueous solution was mixed with the O / W emulsion heated to 50 ° C. Hereinafter, it carried out similarly to the said Example.

(Internal Oil Phase Encapsulation Rate) 0.2% by weight of ethyl γ-linolenate was mixed with the internal oil phase, and the resulting microcapsule oily dispersion was centrifuged to obtain γ-linoleic acid in the outer oil phase. The amount of ethyl linolenate was determined by high performance liquid chromatography. The encapsulation rate was calculated from the following formula using the amount of ethyl γ-linolenate and the amount of ethyl γ-linolenate in the outer oil phase. Encapsulation rate (%) = [(content-content in outer oil phase)
/ Amount] × 100

Example 2 Internal oil phase: (1) Vitamin A palmitate 5% by weight (2) Squalane 9.5 Water phase: (3) POE (60) hydrogenated castor oil 0.5 (4) 1,3-butylene Glycol 10 (5) Carrageenan 1 (6) Deionized water 24 External oil phase: (7) POE methylpolysiloxane copolymer 1 (8) Dimethylpolysiloxane (6 cs) 48 (9) Benton 38 1 Total 100.0

(Preparation method) (1) and (2) were mixed to obtain an internal oil phase. The internal oil phase was gradually added to a mixture of (3), (4) and (6) 0.5% to obtain an oil-in-water-soluble emulsion. (5) was heated and dissolved at 90 ° C. in the remainder of (6) to prepare an aqueous solution of carrageenan, and cooled to 50 ° C. The carrageenan aqueous solution was added to the oil-in-water-soluble emulsion heated to 50 ° C. with stirring to obtain an O / W emulsion (average particle size 0.5 μm).
m). The O / W emulsion was added to (7), (8), (9)
And emulsified at 50 ° C. × 7000 rpm to obtain O /
A W / O emulsion was prepared. This was gradually cooled to room temperature to solidify the carrageenan in the aqueous phase to obtain a microcapsule oily dispersion. The average particle size of the obtained microcapsules was 10 μm, the average particle size of the encapsulated oil droplets was 0.5 μm, and the encapsulation rate of the internal oil phase was 100 μm.
%Met. The breaking strength of the capsule is 200 g / c.
It was m ^2.

Formulation Example 1 O / W cream (microcapsule formulation)

[Table 3] Ingredients Capsule 1 Capsule 2  Inner oil phase: cyclosporin 5-crotamiton 15-vitamin C dipalmitate-2.5 dioctyl sebacate-15 aqueous phase: 1,3-butylene glycol 10 10 POE (60) hydrogenated castor oil 11 agar (AX-200) 5 1.5 Ion-exchanged water 17.5 20 Outer oil phase POE methyl polysiloxane copolymer 11Octamethylcyclotetrasiloxane 49 49

(Microcapsule Production Method) A microcapsule oil-based dispersion was prepared according to the formulation shown in Table 3 in accordance with Example 1.
This was filtered to obtain microcapsules. The capsule breaking strength was all 400 g / cm ² . (Preparation of cream) An O / W cream was prepared according to a conventional method according to the formulation shown in Table 4, and stored at 0 ° C., room temperature and 50 ° C., and the presence or absence of crystal precipitation was observed with the lapse of time for up to one month.

[0053]

[Table 4]  creamComponent ABCD  Stearyl alcohol 66 66 stearic acid 22 22 hydrogenated lanolin 44 44 squalane 9 93 33 octyldodecanol 10 10 10 10 Cyclosporin-2-crotamiton-6 Dioctyl 6 1, 3-butylene glycol 6666 PEG 1500 44 44 POE (25) cetyl alcohol 33 33 33 glyceryl monostearate 222 2 2 Purified water 34 34 52 53 53 capsule 1 (solid content) 20---Capsule 2 (solid content)-20--Preservative proper amount proper amount proper amount proper amountAntioxidant appropriate amount appropriate amount appropriate amount appropriate amount  Precipitation (after 3 days at 0 ° C) No No Yes Yes (1 month after 0 ° C) No No Yes Yes (2 weeks after room temperature) No No Yes Yes (1 month after room temperature) No No Yes Yes (2 weeks at 50 ° C) After) None None None None(After one month at 50 ℃) No No Yes Yes

Drugs such as cyclosporine and vitamin C dipalmitate have poor solubility in a solvent and easily crystallize. Therefore, they can be temporarily dissolved in a solvent by heating or the like, but they can be added over time. In some cases (creams C and D). On the other hand, when microcapsules containing these drugs, such as creams A and B, were mixed, no crystal precipitation was observed. Therefore, the microcapsules of the present invention are very stable, and if they are used, it is possible to stably mix drugs that are difficult to mix conventionally, and that these drugs are released quickly when applied to the skin. Becomes possible. Further, since the microcapsules of the present invention can stably enclose a large amount of water-soluble drug in the aqueous phase, they are also useful for preparations in which water-soluble drugs have conventionally been difficult to mix.

Formulation Example 2 Lipstick (microcapsule formulation) Inner oil phase: Retinol 5% by weight Dioctyl sebacate 15 Aqueous phase: 1,3-butylene glycol 10 POE (60) hydrogenated castor oil 1 Agar (S-5) Reference Signs List 5 Ascorbic acid 2-glucoside 5 Deionized water 12.5 External oil phase: POE methylpolysiloxane copolymer 1 Octamethylcyclotetrasiloxane 49 (Microcapsule production method) Was prepared and filtered to obtain microcapsules (capsule breaking strength 350 g /
cm ² ).

(Preparation of lipstick) Titanium dioxide 5% by weight Red 201 No. 0.6 Red No. 202 1 Red No. 223 0.2 Candelilla wax 9 Solid paraffin 8 Beeswax 5 Carnauba wax 5 Lanolin 11 Castor oil 5.2 2-Ethyl Cetyl hexanoate 20 Isopropyl myristate 10 Microcapsules (solid content) 20 Ion-exchanged water-Glycerin-POE (25) POP (20) 2-tetradecyl ether-Antioxidant Appropriate amount Perfume Appropriate amount

A solid lipstick was prepared by a conventional method. In ordinary lipsticks, it is difficult to formulate an oxidizing agent such as retinol, and it is not possible to formulate a water-soluble humectant such as an ascorbic acid derivative. By using the microcapsules of the present invention, such a drug can be stably compounded in lipstick, so that a lipstick having a wrinkle improvement and moisturizing effect can be obtained.

Formulation Example 3 Blusher Kaolin 20% by weight Titanium Dioxide 4.2 Iron Oxide (Red) 0.3 Red No. 202 0.5 Celesin 15 Liquid Paraffin 15 Isopropyl myristate 5 Microcapsules of Formulation Example 2 (Solid Content) 20 Antioxidant appropriate amount Fragrance appropriate amount

Formulation Example 4 O / W Foundation

[Table 5] Ingredients Foundation A Foundation B  Talc 33 Titanium dioxide 55 Bentonite 0.5 0.5 Microcapsules (solid content) * 10-POE sorbitan monostearate 0.9 0.9 Triethanolamine 11 1 Propylene glycol 10 10 Vitamin E acetate-1 Ion exchange Water 48.4 57.4 Stearic acid 2.2 2.2 Isohexadecyl alcohol 7 7 Glycerin monostearate 22 Liquid lanolin 22 Liquid paraffin 8 8 Preservatives proper amount antioxidant proper amount proper amountFragrance appropriate amount appropriate amount Discoloration (50 ℃, 1 month) No Yes  * A microcapsule of Formulation Example 2 prepared by replacing retinol with vitamin E acetate.

An O / W foundation was prepared by a conventional method, and after storage at 50 ° C. for one month, the presence or absence of discoloration was visually observed. In Foundation B, in which vitamin E acetate was directly blended, discoloration was observed. This is presumably because vitamin E was decomposed by metal ions contained in the inorganic pigment. On the other hand, no discoloration was observed in Foundation A containing microcapsules containing vitamin E acetate.

Formulation Example 5 Jelly-like peel-off pack polyvinyl alcohol 15% by weight carboxymethylcellulose 5 1,3-butylene glycol 5 ethanol 5 POE oleyl alcohol 0.5 Microcapsules of Formulation Example 2 (solid content) 10 ion-exchanged water 59.5

A jelly-like peel-off pack was prepared by a conventional method. Since ordinary jelly packs are water-based, it is difficult to mix oils and oily drugs, but with the microcapsules of the present invention, oils and oily drugs can be stably compounded and coated. Then, a pack is obtained in which these inclusions are released quickly.

Formulation Example 6 Capsule Formulation Sheet (1) 1,3-butylene glycol 15% by weight (2) Polyvinyl alcohol 5 (3) Microcapsules of Formulation Example 2 (solid content) 50 (4) Ethanol 10 (5) PEG6000 3 (6) PEG1200 2 (7) POE (25) hydrogenated castor oil 5 (8) stearic acid 10

(Preparation method) (1), (2), (5) and (6) were stirred and dissolved, and (4), (7) and (8)
Was added, and (3) was further added and stirred to obtain a microcapsule-mixed liquid. The liquid agent was impregnated into a sheet such as a nonwoven fabric to obtain a sheet-like product.

Formulation Example 7 Deodorant powder spray (capsule formulation) Internal oil phase: (1) zinc paraphenolsulfonate 4.25% by weight (2) squalane 4 (3) triclosan 0.25 (4) isopropyl myristate 2. 5 aqueous phase: (5) 1,3-butylene glycol 10 (6) POE (60) hydrogenated castor oil 1 (7) agar (AX-100) 1 (8) gellan gum 0.3 (9) citric acid 0.1 (10) Sodium citrate 0.1 (11) Ascorbic acid 2-glucoside 2.5 (12) Deionized water 24.0 (13) Antioxidant Appropriate amount External oil phase: (14) POE methyl polysiloxane copolymer 1 (15) Octadecylcyclotetrasiloxane 49

(Capsule manufacturing method) (5), (6) and (1)
2) The inner oil phase was gradually added to the 0.5% mixture to obtain an oil-in-water-soluble emulsion. (7), (8),
(11) and (13) were dissolved in 10% of (12) with heating at 90 ° C. to prepare a gelling agent aqueous solution, which was cooled to 50 ° C. The aqueous solution of the gelling agent was added to the oil-in-water-soluble emulsion heated to 50 ° C. while stirring, and
/ W emulsion was obtained. The O / W emulsion was added to the outer oil phase and emulsified at 50 ° C. to prepare an O / W / O emulsion. Further, an aqueous solution in which the remaining components (9), (10) and (12) were mixed and dissolved was added, and after sufficient stirring, the mixture was gradually cooled to room temperature to prepare a microcapsule oily dispersion. Thus, microcapsules were obtained (rupture strength: 100 g / cm ² ).

(Spray Stock Formulation) Aluminum chlorohydrate 30% by weight Silicic anhydride 15 Silicon treated talc 15 Zinc oxide 5 Microcapsules (solid content) 20 Dimethylpolysiloxane 12 Sorbitan stearate 3 (Spray process) 10 parts by weight of stock solution 90 parts by weight of LPG were filled in a spray can.

Formulation Example 8 Translucent lotion (1) 1,3-butylene glycol 6% by weight (2) glycerin 5 (3) polyethylene glycol 400 3 (4) olive oil 0.5 (5) POE (20) sorbitan mono Stearic acid ester 1.5 (6) Ethanol 5 (7) Microcapsules (Example 1-1, solid content) 5.3 (8) Purified water 73.7 (9) Perfume proper amount (10) Preservative proper amount

(Preparation method) (1) was added to (8) (aqueous phase). (2) to (5) and (9) to (10) were added to (6) and mixed at room temperature (alcohol phase). The alcohol phase was added to the aqueous phase, and (7) was further added and stirred to obtain a lotion.

Formulation Example 9 O / W type emollient lotion (1) Stearic acid 2% by weight (2) Cetyl alcohol 1.5 (3) Vaseline 4 (4) Squalane 5 (5) Glycerol tri-2-ethylhexanoate 2 (6) Sorbitan monooleate 2 (7) Dipropylene glycol 5 (8) Polyethylene glycol 1500 3 (9) Triethanolamine 1 (10) Microcapsules (Example 1-2, oily dispersion) 10 (11 ) Purified water 64.5 (12) Perfume proper amount (13) Preservative proper amount

(Production method) (11) (7), (8),
(9) was added and heated to 70 ° C. (aqueous phase). (1)-
(5) was mixed and dissolved, (6), (12) and (13) were added, and the mixture was heated to 70 ° C. (oil phase). The oil phase was added to the aqueous phase, mixed and emulsified with a homomixer, and (10) was added to further mix. After degassing, filtration and cooling, an emollient lotion was obtained.

Formulation Example 10 W / O type massage cream (1) Microcrystalline wax 9% by weight (2) Solid paraffin 2 (3) Beeswax 3 (4) Vaseline 5 (5) Reduced lanolin 5 (6) Squalane 30 (7 ) Hexadecyl adipate 1 (8) Propylene glycol 5 (9) Glycerin monooleate 3.5 (10) POE (20) Sorbitan monooleate 1 (11) Microcapsules (Example 1-2, oil dispersion Material) 4 (12) Purified water 30.5 (13) Perfume proper amount (14) Preservative proper amount

(Preparation method) After heating and dissolving (1) to (7),
(9), (10), (13), and (14) are added, and 70
° C (oil phase). Add (8) to (12) and add 70
C. (aqueous phase). After mixing and emulsifying the oil phase and the aqueous phase with a homomixer, (11) was added and further mixed, deaerated, filtered and cooled to obtain a cream.

Formulation Example 11 W / O type emollient cream (1) Squalane 20% by weight (2) Cetyl isooctanoate 8.5 (3) Microcrystalline wax 1 (4) Organically modified clay mineral 1.3 (5) POE glycerol triisostearate 0.2 (6) glycerin 5 (7) microcapsules (Example 1-1, oily dispersion) 5 (8) purified water 59 (9) fragrance appropriate amount (10) preservative appropriate amount

(Preparation method) After heating and dissolving (1) to (3),
(4), (5), (9), and (10) were added, the temperature was adjusted to 70 ° C., and the mixture was uniformly dispersed and dissolved to obtain an oily gel. (8)
(6) was added to the mixture, and the mixture was adjusted to 70 ° C (aqueous phase). The aqueous phase was gradually added to the oily gel with sufficient stirring, and uniformly mixed with a homomixer. Then, (7) was added, and the mixture was further mixed, deaerated, filtered, and cooled to obtain a cream.

Formulation Example 12 Moisture gel (1) 7% by weight of dipropylene glycol (2) Polyethylene glycol 1500 8 (3) Carboxyvinyl polymer 0.4 (4) Methyl cellulose 0.2 (5) POE (15) Oleyl ether 1 (6) Potassium hydroxide 0.1 (7) Microcapsules (Example 1-1, solid content) 1 (8) Purified water 82.3 (9) Perfume appropriate amount

(Production method) (6) was dissolved in a part of (8) to obtain an aqueous alkali solution. (3) in the rest of (8),
After dissolving (4) uniformly, (2) was added (aqueous phase). Add (5) to (1) and heat dissolve at 50 ° C.
(9) was added. To this, the aqueous phase was gradually added with stirring, an aqueous alkali solution was added, and after stirring, (7) was added and the mixture was sufficiently stirred to obtain a gel.

Formulation Example 13 O / W emollient cream (capsule formulation) Inner oil phase: (1) Squalane 10% by weight (2) Lecithin 1 Aqueous phase: (3) POE (60) Hardened castor oil 0.5 (4) Glycerin 10 (5) Time extract 1 (6) Agar (PS-84) 1 (7) Deionized water 26.5 Oil phase: (8) POE methyl polysiloxane copolymer 0.5 (9) Dimethyl polysiloxane ( 6cps) 49.5

(Capsule manufacturing method) (1) and (2) at 50 ° C.
To dissolve into an internal oil phase. (3), (4),
(5) and (7) The internal oil phase was gradually added to the 0.5% mixture to obtain an oil-in-water-soluble emulsion. (6)
Was dissolved in 26% by heating at 90 ° C. to prepare an aqueous agar solution, which was cooled to 50 ° C. The agar aqueous solution was added to the oil-in-water-soluble emulsion heated to 50 ° C. while stirring to obtain an O / W emulsion (average particle size: 0.5 μm). The O / W emulsion was added to the mixture of (8) and (9) and emulsified while maintaining the temperature at 50 ° C.
A W / O emulsion was prepared. This was gradually cooled to room temperature and the aqueous phase agar was solidified to obtain a microcapsule oily dispersion.

(Emollient cream formulation) (1) Squalane 5% by weight (2) Acrylic acid / alkyl methacrylate copolymer 0.1 (3) Carboxyvinyl polymer 1.0 (4) Sodium hydroxide 0.2 (5 ) Glycerin 15 (6) Microcapsules (solid content) 8 (7) Purified water 69.7 (8) Perfume proper amount (9) Preservative proper amount (Emollient cream production method) (6) to (2) to (5)
And (9) were added to obtain an aqueous phase. (8) was added to (1) to obtain an oil phase. The oil phase was added to the aqueous phase, mixed and emulsified with a homomixer, and (6) was added to further mix. Degassed and filtered to obtain an O / W emollient cream.

Formulation Example 14 W / O emollient cream (1) Squalane 5% by weight (2) Vaseline 5 (3) POE glyceryl isostearate 3 (4) Glyceryl isostearate 3 (5) Glycerin 10 (6) Microcapsules (Formulation) Oily dispersion of Example 13) 10 (7) Purified water 63 (8) Perfume proper amount (9) Preservative proper amount

(Preparation method) (5) and (9) were added to (7), and the mixture was adjusted to 70 ° C. (aqueous phase). (1) to (2) ~
(4) and (8) were added, dissolved by heating, and adjusted to 70 ° C. (oil phase). After mixing and emulsifying the oil phase and the aqueous phase with a homomixer, (6) was added and further mixed, deaerated, filtered and cooled to obtain a W / O emollient cream.

[0083]

According to the present invention, microcapsules having fine encapsulated oil droplets and excellent in stability of the capsule and release of the encapsulated oil droplets upon application can be obtained. The production of the microcapsules of the present invention is simple, efficient without loss of the inner oil phase, and the capsule diameter can be easily controlled.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a microcapsule according to the present invention.

[Explanation of Signs] 1 Included oil droplet (inner oil phase) 2 Microcapsule 3 Outer oil phase

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) A61K 7/00 A61K 7/00 U 7/025 7/025 7/031 7/031 9/50 9/50 B01J 13/06 B01J 13/02 E (72) Inventor Toshio Yanagi 1050 Nippa-cho, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture F-term in Shiseido Daiichi Research Center (reference) 4C076 AA61 AA64 BB31 CC18 DD08 DD37 DD38 DD41 DD44 DD46 EE23 EE27 EE30 EE51 GG21 4C083 AA082 AA112 AA122 AB032 AB172 AB212 AB222 AB232 AB242 AB372 AB432 AB442 AC012 AC022 AC062 AC122 AC242 AC352 AC422 AC432 AC442 AC542 AC792 AC842 AD042 AD112 AD152 AD211 AD212 AD262 AD351 AD352 AD392 CC512 AD572 CC12 CC13 CC17 DD01 DD08 DD11 DD12 DD14 DD21 DD23 DD31 DD33 DD34 DD41 EE06 EE07 FF01 4G005 AA01 AB09 AB14 AB15 AB17 AB21 AB30 BA20 BB06 BB13 DA09X DA09Z DB02W DB06X DB06Z DB08X DB08Z DB09X DB09Z DB12X DB12Z DB13X DB13Z DB14X DB14Z DB17X DB17Z DB22X DB23X DB27W DB27X DC03X DC15X DC18W DC26X DD47Z DD59X DD59Z DE08X DE08Z

Claims (14)

[Claims] 1. An oil droplet having an average particle size of 0.01 to 3 μm is included therein, the encapsulating agent is a hydrophilic polymer gelling agent, and the breaking strength of the capsule is 10 to 500 g / cm ^2. Microcapsules characterized by the following. 2. The microcapsule according to claim 1, wherein the main component of the encapsulating agent is a hydrophilic polymer gelling agent which solidifies by heating and cooling. 3. The microcapsule according to claim 1, wherein the hydrophilic polymer gelling agent is agar. 4. The microcapsule according to claim 1, wherein the hydrophilic polymer gelling agent is carrageenan. 5. The microcapsule according to claim 1, wherein the microcapsule contains a hydrophilic nonionic surfactant and a water-soluble solvent. 6. An oil dispersion of microcapsules, wherein the microcapsules according to claim 1 are dispersed in an oil phase. 7. The microcapsule oily dispersion according to claim 6, wherein an O / W emulsion is prepared from an inner oil phase and an aqueous phase containing a hydrophilic polymer gelling agent. O /
A microcapsule oily dispersion obtained by preparing a W / O emulsion and solidifying an aqueous phase of the O / W / O emulsion. 8. The microcapsule oil-based dispersion according to claim 7, wherein the O / W emulsion is obtained by adding an internal oil phase to a water-soluble solvent containing a hydrophilic nonionic surfactant and adding the oil in a water-soluble solvent. A microcapsule oil-based dispersion, which is an O / W emulsion prepared by preparing an emulsion of the type and adding an aqueous solution of a hydrophilic polymer gelling agent to the oil-in-water-soluble emulsion. 9. The microcapsule according to claim 1, wherein the microcapsule is obtained by removing an outer oil phase of the microcapsule oil dispersion according to claim 7. Microcapsules. 10. A microcapsule or an oily dispersion thereof according to claim 1, wherein the capsule contains an oily drug. 11. A cosmetic comprising the microcapsule or the oily dispersion thereof according to claim 1. 12. A solid cosmetic comprising the microcapsule or the oily dispersion thereof according to claim 1. 13. An internal oil phase and an aqueous phase in which a hydrophilic polymer gelling agent which solidifies by heating and cooling is heated and dissolved in advance, and has an average particle diameter of not less than the solidification temperature of the gelling agent. 01
An O / W emulsion preparation step of preparing an O / W emulsion of about 3 μm, and an O / W / O emulsion preparation step of dispersing and emulsifying the O / W emulsion in an outer oil phase at a temperature not lower than the solidification temperature of the gelling agent. An encapsulation step of cooling the O / W / O emulsion below the solidification temperature of the gelling agent to solidify the aqueous phase, wherein the gel prepared from the aqueous phase has a breaking strength of 10-5.
A method for producing microcapsules, characterized in that the microcapsules are 00 g / cm ² . 14. The method according to claim 13, wherein
An O / W emulsion preparation step, in which an internal oil phase component is added to a water-soluble solvent containing a hydrophilic nonionic surfactant to prepare an oil-in-water-soluble emulsion, A method for producing microcapsules, comprising a step of mixing a hydrophilic polymer gelling agent, which solidifies by heating and cooling, with an aqueous solution in which the gelling agent has been heated and dissolved in advance at a temperature not lower than the solidification temperature of the gelling agent.