JP2002301357A - Microcapsule and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a general-purpose microencapsulating technique by which microcapsules housing a large amount of a core material can be obtained because the dissipation of the core material in the production of microcapsules is slight and the particle diameter of the microcapsules is easily controlled according to the purpose for which they are used. SOLUTION: The method for producing microcapsules includes a step for preparing a first emulsion in which a porous core material carrier having objective activity and adsorbing and holding a core material is dispersed in an organic solvent (or water) containing a dissolved hydrophobia (or hydrophilic) film forming polymer, a step for preparing a second emulsion in which the first emulsion is dispersed in water (or oil) by adding the first emulsion to an aqueous solution (or an oil solution) and a step for obtaining microcapsules housing the core material adsorbed and held on the core material carrier in a film comprising the polymer by removing the organic solvent (or water) from the second emulsion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of microcapsules, and more particularly to a novel method for producing microcapsules utilizing a submerged drying method and microcapsules obtained by the method.

[0002]

2. Description of the Related Art Microcapsules are microparticles having a particle size on the order of micrometer (μm) in which a liquid or solid core substance having a desired activity is encapsulated in a film made of a polymer. , Immobilized enzyme,
Widely used for carbonless copy paper and adhesives.

[0003] Typical methods for producing microcapsules include (1) a polymerization method in which a core material is encapsulated in a polymer film obtained by polymerizing a monomer at an interface or in situ, and (2) a polymerization method of a core material and a polymer. A phase separation method in which a core substance is encapsulated by a polymer phase-separated by adding an electrolyte, a pH adjusting agent, another organic solvent, or the like to an aqueous solution or an organic solvent solution, and (3) a drying method in a liquid. Among them, the submerged drying method is the former (1) and (2)
It is particularly suitable for microencapsulation of substances that are sensitive to changes in environment and conditions because they are not subjected to intense chemical reactions and do not involve addition of reactive substances.

The in-liquid drying method is also called an interfacial precipitation method or a secondary emulsion method. A (W / O) type emulsion is prepared from a solution of a core substance and a hydrophobic polymer, and this is added to another aqueous solution. To obtain a ((W / O) / W) type composite emulsion, and removing the solvent of the polymer from the composite emulsion, or conversely, first, the (O / O / W) type emulsion was prepared and dispersed in an oil solution ((O / W) /
An O) type composite emulsion is prepared, and water is removed from the composite emulsion to produce microcapsules having a core substance encapsulated in a polymer film.

[0005] In the production of microcapsules by such a conventional in-liquid drying method, the core substance is used as it is. That is, in producing microcapsules by the former method of drying in water in water, an aqueous solution of a core substance is added to a hydrophobic polymer to prepare a (W / O) type emulsion, and When the microcapsules are produced by the in-liquid drying method in (1), an oily core substance or an oil in which the core substance is dissolved is added to an aqueous solution of a hydrophilic polymer to prepare an (O / W) type emulsion. . However, according to such a method, the core substance is lost during the production of the microcapsules, and therefore, the amount of the core substance encapsulated in the finally obtained microcapsules is small, and pollution is caused by mixing in the waste liquid. It can also be a cause. Furthermore, depending on the core substance used, there are those that dissolve the polymer that forms the film,
In some cases, capsules are not formed. Further, the conventional microencapsulation method is intended only for microcapsules having a particle size within a limited range, and it is generally difficult to control the particle size of the microcapsules.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a microcapsule containing a large amount of a core substance with little loss of the core substance during the production of the microcapsules. It is an object of the present invention to provide a new microencapsulation technology that is easy to control and versatile.

[0007]

Means for Solving the Problems The present inventor has devised a new type of microencapsulation technique which can achieve the above-mentioned object by devising a submerged drying method. Thus, according to the present invention, a core material having the desired activity, a core material carrier capable of adsorbing and holding the porous core material, a hydrophobic film-forming polymer, and an organic solvent capable of dissolving the polymer, A first emulsion [hereinafter referred to as (S / O) emulsion or (S / O)] in which a core substance carrier having adsorbed and retained a core substance is dispersed in an organic solvent in which a polymer is dissolved.
A phase: S means solid; a second emulsion in which the first emulsion is dispersed in water by adding the first emulsion to an aqueous solution [hereinafter (( (S / O) / W) emulsion or ((S / O) / W) phase); and removing the organic solvent from the second emulsion to form a core in a polymer coating. Adsorbed on substance carrier
A method for producing a microcapsule including a step of obtaining a microcapsule containing a held core substance is provided [hereinafter, the method for producing a microcapsule of the present invention is referred to as a ((S / O) / W) type microcapsule. Chemical method).

Further, according to the present invention, the core substance is adsorbed from a core substance having a desired activity, a porous core substance carrier capable of adsorbing and retaining the core substance, a hydrophilic film-forming polymer and water. The first emulsion in which the held core substance carrier is dispersed in water in which the polymer is dissolved [hereinafter, (S / W)
Emulsion or (S / W) phase)
A second emulsion in which the first emulsion is added to an oil solution to disperse the first emulsion in oil [hereinafter referred to as ((S / W) / O) emulsion or ((S / W ) / O) phase); and removing the water from the second emulsion and enclosing the core material adsorbed and retained on the core material carrier in a polymer film. There is provided a method for producing microcapsules, which comprises a step of obtaining capsules. [Hereinafter, this method for producing microcapsules of the present invention will be referred to as ((S / W) / O) microencapsulation method. There is.

A particularly preferred embodiment of the method for producing microcapsules according to the present invention uses sumithion (fenitrothion) as a core substance, activated carbon as a core substance carrier, poly-ε-caprolactam as a polymer, and ethyl acetate as an organic solvent ((S / O) / W) microencapsulation method, in which Sumithion having an encapsulation rate of 30% or more is encapsulated in a film made of poly-ε-caprolactam, and Sumithion encapsulation having a particle size of 20 μm to 5 mm. Degradable microcapsules are obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One of the important features of the method for producing microcapsules of the present invention is that the core substance is adsorbed (impregnated) on a porous carrier in advance, and the core substance is stably retained on the carrier. After preparing one emulsion, it is to provide for preparation of a second emulsion. As a result, the core material becomes a continuous phase of the first emulsion [((S / O) /
An organic solvent phase in which the polymer is dissolved in the W) type microencapsulation method, and an aqueous phase in which the polymer is dissolved in the ((S / W) / O) type microencapsulation method]
Into the continuous phase of the emulsion (aqueous phase in ((S / O) / W) microencapsulation method and oil phase in ((S / W) / O) microencapsulation method) This greatly reduces the loss of the core substance during the production of the microcapsules, and provides a microcapsule having a very high core substance encapsulation rate.

For example, when activated carbon is used as a core substance carrier in the production of Sumithion-encapsulated microcapsules, which is a preferred embodiment to which the present invention is applied, most (about 95%) of Sumithion (core substance) charged at the time of microcapsule production is used. It has been confirmed that microcapsules having a high encapsulation rate of 30 to 60% can be obtained (up to about 15% in the conventional method). (Here, the encapsulation rate is expressed as a percentage of the weight of the core substance with respect to the weight of the whole microcapsule.) Also, the core substance (Sumithion) does not dissolve the film-forming polymer, and the microcapsules are surely dissolved. A capsule is formed.

The carrier of the core material has a porosity capable of adsorbing and holding the core material, and when used in the ((S / O) / W) type microencapsulation method, is used in an organic solvent. When used in the ((S / W) / O) microencapsulation method, various materials that can be stably dispersed in water can be used. A material suitable as a core substance carrier used in the ((S / O) / W) type microencapsulation method is a lipophilic porous solid represented by activated carbon. Further, a material suitable as a core substance carrier used in the ((S / W) / O) type microencapsulation method is a hydrophilic porous solid represented by silica gel.

The ((S / O) / W) microencapsulation method according to the present invention comprises various hydrophobic film-forming polymers known to form microcapsule films and their solubility in the polymer. Can be carried out in combination with an organic solvent excellent in the above. For example, as the hydrophobic polymer, polystyrene can be used in combination with an organic solvent such as methyl chloride or carbon tetrachloride, and ethyl cellulose can be used in combination with an organic solvent such as benzene or cyclohexane, but is not limited to these examples. Absent.

On the other hand, if the ((S / W) / O) microencapsulation method of the present invention is carried out, various hydrophilic film-forming polymers known to form microcapsule films can be used. To manufacture microcapsules. Such hydrophilic film-forming polymers include, but are not limited to, gelatin, gum arabic, polyvinyl alcohol, polysaccharides, and the like.

In producing microcapsules according to the present invention, it is preferable to use a biodegradable film-forming polymer depending on the use of the microcapsules. In this regard, the ((S / O) / W) microencapsulation method of the present invention is suitable for producing pesticides comprising sustained-release biodegradable microcapsules containing an insecticide such as Sumithion. I have. A particularly preferable combination of a polymer and an organic solvent for obtaining such microcapsules is a case where poly-ε-caprolactam, which is a biodegradable polymer, is used together with ethyl acetate as an organic solvent, and in addition, polylactic acid is acetonitrile. It can also be used with.

According to the present invention, various liquid or solid core substances having an activity according to the intended use of the microcapsules, such as the insecticides described above, Various microcapsules containing the pharmaceutically active ingredient, enzyme, and the like can be obtained. FIG. 1 schematically shows a process for producing microcapsules by the ((S / O) / W) type microencapsulation method or the ((S / W) / O) type microencapsulation method according to the present invention. is there.

As shown in FIG. 1, to produce microcapsules according to the method of the present invention, first, a core substance is adsorbed from a core substance, a core substance carrier, a hydrophobic film-forming polymer, and an organic solvent. A first emulsion in which the retained core substance carrier is dispersed in an organic solvent in which a polymer is dissolved (in the case of ((S / O) / W) type microencapsulation);
Alternatively, a first emulsion [((S / W)) in which a core substance, a core substance carrier, a hydrophilic film-forming polymer, and a core substance carrier adsorbing and holding the core substance from water are dispersed in water in which the polymer is dissolved. / O) type microencapsulation method]. Such emulsions are generally
Solution in which a hydrophobic film-forming polymer is dissolved in an organic solvent [((S / O) / W) type microencapsulation method]
Or an aqueous solution in which a hydrophilic film-forming polymer is dissolved [((S / W) / O) type microencapsulation method]
After adding the core substance, the mixture is obtained by adding the core substance carrier and sufficiently stirring. At this time, if necessary, a dispersion stabilizer (emulsifier) to stabilize the emulsion.
Add.

Next, the first emulsion thus prepared is mixed with a sufficiently stirred aqueous solution [((S / O)
/ W) type microencapsulation method] or an oil solution (((S / W) O) type microencapsulation method), whereby the second emulsion in which the first emulsion is dispersed in water. [((S / O) / W) microencapsulation method] or a second emulsion in which the first emulsion is dispersed in oil [((S / W) / O) microencapsulation method] is obtained. . That is, as schematically shown in FIG. 1, the ((S / O) / W) type microencapsulation method comprises a core substance carrier that has adsorbed and retained a core substance and an organic solvent / polymer present around the core substance carrier. A second emulsion (composite emulsion) in which fine particles of the (S / O) phase are dispersed in water, and ((S / W) / O)
In the micro-encapsulation method, a second emulsion (composite emulsion) in which fine particles of a (S / W) phase composed of water / polymer present around the core material carrier having adsorbed and held the core material dispersed in oil is used. Is formed.

An aqueous or oil solution serving as a medium for such a second emulsion is added in advance with a dispersion stabilizer (emulsifier).
Is preferably added. As the dispersion stabilizer (emulsifier) used when preparing the first emulsion and the second emulsion, a nonionic surfactant is preferable, but other types of emulsifiers can be used in combination as needed. In the ((S / W) / O) microencapsulation method, the oil solution serving as the medium of the second emulsion is generally a poorly water-soluble organic solvent. Can also be contained.

The second emulsion prepared as described above is then treated with a solvent [((S / O) /
In the case of the microencapsulation method (W), an organic solvent ((S
/ W) / O) type microencapsulation method is subjected to a step of removing water]. This solvent removal is performed by heating, decompression,
It is carried out by solvent extraction, cooling, addition of dry powder, freeze drying and the like.

As the solvent removal in the ((S / O) / W) microencapsulation method, it is generally preferable to employ heating, decompression or a combination of these treatments (heating under reduced pressure). By such an operation, (S / O)
The organic solvent of the phase dissolves in the water (external water phase) constituting the medium (continuous phase) of the ((S / O) / W) emulsion, evaporates from the surface of the external aqueous phase, and the polymer evaporates. And settle around the core material carrier that adsorbs and retains the core material to form a film. On the other hand, in the ((S / W) / O) microencapsulation method, when removing the solvent (water) in which the polymer is dissolved, the oil constituting the medium (continuous phase) of the second emulsion is used. Since the boiling point of the solution is often lower than that of water, heating or decompression is generally not preferred. For solvent removal (water removal), it is preferable to use means such as cooling, addition of a dry powder, and solvent extraction. .

After the solvent in which the polymer is dissolved is removed as described above, an appropriate purification treatment (removal of the solution constituting the continuous phase of the second emulsion, removal of impurities adhering to the film surface) ) And drying treatment, a microcapsule in which the core substance adsorbed and held by the core substance carrier is encapsulated in the polymer film is obtained.

According to the present invention, it is possible to prepare a stable emulsion by adsorbing and holding the core substance on the core substance carrier (both the first emulsion and the second emulsion). By changing various conditions in the preparation of an emulsion, it is easy to prepare emulsions having different particle sizes. As a result,
Their preparation conditions, in particular, the addition amount (concentration) of the core substance, the addition amount (concentration) of the core substance carrier, the stirring speed (stirring strength) during the preparation of the first emulsion and / or the preparation of the second emulsion, By changing the addition amount (concentration) of the dispersion stabilizer (emulsifier) during the preparation of the first emulsion and / or the preparation of the second emulsion, the volume fraction of the dispersed phase relative to the continuous phase in the second emulsion, and the like, Control of the particle size of the microcapsules to be obtained becomes easy.

For example, as a preferred specific example to which the present invention is applied, in the case of producing biodegradable and sustained-release microcapsules containing Sumithion using activated carbon as a core substance carrier as described in Examples below, The following has been found. (1) If the added amount of the core substance carrier is too small, the capsule itself may not be formed. When the core substance carrier is added in an amount larger than that capable of forming a capsule, the larger the amount of the core substance and / or the core substance carrier added, the larger the particle size of the obtained microcapsules. (2) The particle size of the obtained microcapsules decreases as the stirring speed during the preparation of the first emulsion and / or during the preparation of the second emulsion increases. (3) If the amount of the surfactant added during the preparation of the first emulsion is too large, solidification does not proceed and microcapsules are not formed. (4) The higher the concentration of the surfactant in preparing the second emulsion, the smaller the particle size of the obtained microcapsules. (5) In the case of sustained-release microcapsules, the larger the particle size, the longer it takes to release the core substance, and by controlling various conditions in the emulsion preparation as described above, the particle size of the microcapsules is controlled. Thereby, the sustained release property can be controlled.

As described above, according to the present invention, the core substance can be included in a large amount, and the particle size is controlled over a wide range, so that the core substance has flexibility depending on the mode of use and is economical. Various types of microcapsules which are preferable in terms of properties and environment can be obtained. For example, the microcapsules containing Sumithion as the core substance obtained by the present invention have a large encapsulation amount, so that an effect can be obtained with a small amount of spraying, and the optimum spraying method (aqueous solution) can be obtained by arbitrarily controlling the particle size. Spraying or solid spraying), and can be used as an excellent pesticide (pesticide) capable of controlling the sustained release property and gradually releasing a large amount of inclusions over a long period of time to reduce the number of times of spraying. Furthermore, since most of the core material as a raw material can be included in the production of such microcapsules, it is economical with little loss at the time of production and the pollution by disposal is small. In addition, by using a biodegradable polymer as the film, the film is decomposed after spraying and does not remain on the soil, and this also reduces environmental pollution.

[0026]

EXAMPLES The characteristics of the present invention will be more specifically described below.
An embodiment will be described below, but the present invention is not limited to this embodiment.
There is no restriction.Example 1 Production of Sumithion-Encapsulated Microcapsules  PCL (poly-ε-caprolactam) and ethyl acetate
Dissolves nitronitrone (MEP: Sumithion) at a specified concentration
The resulting mixture was used as an organic phase. In 480 ml of distilled water
Surfactant Q12-S (monolaurin as a dispersion stabilizer
Acid decaglycerin) at a predetermined concentration and TCP. 10 to 60m
l (1.1 wt%) was used as the external aqueous phase.
A predetermined amount of activated carbon is added to the organic phase, and 3
The mixture was stirred at 23K and 5000 rpm for 10 minutes. This S /
O solution (S / O emulsion) in a reactor at 323K
Heated to 500 rpm and added to the external aqueous phase stirred at 500 rpm.
(S / O) / W emulsion was prepared. S / O solution
5 minutes after adding to the external aqueous phase,
The aqueous phase was collected. Next, the reactor is operated by a diaphragm pump.
3 hours while sucking so that the inside becomes 722 mmHg
Stir to evaporate the ethyl acetate solvent (dry in liquid)
Preparation of microcapsules by filtration, filtration and drying
did. Using the microcapsules prepared in this way
The characteristics of the capsule were studied.

The relationship between the particle size of the microcapsules prepared as described above and various preparation conditions is shown in FIGS. In addition, the meaning of the code | symbol shown in a figure is as follows. C _PCL : Concentration of film-forming polymer, poly-ε-caprolactam: PCL (g) / organic phase (g) (organic phase: ethyl acetate + PCL + MEP) Mw _PCL : Molecular weight of film-forming polymer, poly-ε-caprolactam C _MEP : Concentration of core substance and sumithion: MEP (g) /
Organic phase (g) C _Q12S : Surfactant, concentration of Q12-S: Q12-
S (g) / outside water phase (g) (outside water phase: distilled water + TCP.1)
0 + Q12-S) W _TCP : dispersion stabilizer, TCP. 10: TCP.
10 (g) / outer aqueous phase (g) W _{(S / O)} : core substance carrier, concentration of activated carbon: activated carbon (g) / (activated carbon + organic phase) (g) φ _{(S / O) / W} : ( (S / O) / W) Volume fraction of dispersed phase (S / O phase) to external aqueous phase (continuous phase) in emulsion D: Particle size of emulsion or particle size of microcapsules

FIGS. 2 to 5 show that the particle size of the emulsion ((S / O) / W emulsion) corresponds to the particle size of the microcapsules finally obtained. FIG. 2 shows that the particle size of the emulsion and microcapsules decreases with the concentration of surfactant during the preparation of the second emulsion. FIG. 3 shows that the particle size of the emulsion and the particle size of the microcapsules decrease with increasing volume fraction of the dispersed phase relative to the external aqueous phase during the preparation of the second emulsion. FIG. 4 also shows that the particle size of the emulsion and microcapsules increases with increasing concentration of the film-forming polymer during preparation of the first emulsion. Furthermore, FIG. 5 shows that the particle size of the emulsion and microcapsules tends to decrease (especially at low concentrations) as the concentration of the core substance carrier (activated carbon) during the preparation of the first emulsion increases.

[0029]Example 2: Sustained release rate measurement test  As shown in Example 1, according to the present invention,
By changing the conditions during the preparation of capsules,
Control the particle size of the coating
The particle size of the black capsule can be controlled. And
In the case of sustained release microcapsules, the microcapsule
By controlling the particle size of
Release can also be controlled. FIG. 6 and FIG.
Sumithion-encapsulated microcapsules prepared as in Example 1
Release rate of Sumithion (MEP), the core substance of water, into water
It shows the result of measuring the degree. That is, FIG.
Is the concentration of the film-forming polymer as in FIG.
As the particle size of the microcapsules increases,
Accordingly, the sustained release rate is small (A in FIG. 6),
Is also small (FIG. 6B), and the inclusions (Sumithio
) Is released.

FIG. 7 shows that, as shown in FIG. 2, the particle size of the microcapsules increases as the concentration of the surfactant decreases during the preparation of the emulsion. A) and the amount of sustained release (B in FIG. 7) are small, indicating that sumithion is released slowly.

In the test for measuring the sustained release rate as shown in FIGS. 6 and 7, the solubility of sumithion in water was about 300 p.
It was measured by the following method, worried about saturation due to its small amount of pm, and 0.10 g of Sumithion-containing microcapsules was added to 300 ml of distilled water, shaken for a certain period of time, and then the concentration of Sumithion in the aqueous solution was measured. Was measured.
After that, the whole amount of the aqueous solution is replaced with fresh distilled water, shaken again for a certain period of time, and after measuring the concentration, the entire amount of the aqueous solution is replaced with fresh distilled water. Repeat this operation
The concentration of sumithion in the aqueous solution was measured to determine the amount of sumithion that was gradually released from the microcapsules into the aqueous solution. The sustained release amount and the sustained release rate were determined from the following equations. Sustained release amount = total amount of sumithion that has been sustainedly released into the aqueous solution from the start of sustained release to an arbitrary time. Sustained release rate = sustained release amount / amount of sumithion encapsulated in microcapsules at the time of preparation

[0032]Example 3: Insecticidal test  Sumithion-encapsulated microcaps prepared as in Example 1.
Insecticidal effect of cells on the larvae of Scarabaeidae
Was examined by the residual effect of the soil admixture treatment. That is,
Mix microcapsules of a predetermined concentration in
0 and 30 days later release 10 chafers
After 7 days, the mortality rate was examined. Table 1 shows the results.
Shown in In the table, Sumithion MC refers to
Sumithion-encapsulated microcapsules prepared as in Example 1.
No. 1 is the average particle size of about 155μm, encapsulation rate
0.32% microcapsules, no. 2 is about average particle size
81 μm, 0.32% encapsulation microcapsules
You. In addition, Sumithion EC is the same for comparison.
No microencapsulation tested for insecticidal effect
It is a commercially available Sumithion.

[0033]

[Table 1]

As shown in Table 1, in Sumithion EC, the mortality rate of the 30-day release was lower than that of the 10-day release, and a time-dependent decrease in the insecticidal effect was observed. When the microcapsules were used as an insecticide, the insecticidal effect was increased or maintained with the passage of days, which is presumed to be due to the sustained release of the active ingredient (Sumithion).

[0035]Example 4: phytotoxicity test  Using the drug used in Example 3 to prevent phytotoxicity to cabbage
Examined. Table 2 shows the results. As shown in Table 2
In addition, Sumithion EC is a severe drug at high concentration (250 times)
Harm was observed, and its level was reduced as the concentration decreased.
However, phytotoxicity was observed up to 1000 times. In contrast,
Sumithion-encapsulated microcapsules according to the present invention are
o. 1, No. 2 Both are phytotoxic compared to Sumithion EC
The degree is reduced, no phytotoxicity at 1000 times is recognized,
It is understood that this is an excellent insecticide from the viewpoint of phytotoxicity.

[0036]

[Table 2]

[Brief description of the drawings]

FIG. 1 schematically shows a process for producing a microcapsule according to the present invention.

FIG. 2 shows an example of the relationship between the surfactant concentration and the particle size of the emulsion and microcapsules when producing microcapsules according to the present invention.

FIG. 3 shows an example of the relationship between the volume fraction of the dispersed phase with respect to the external aqueous phase and the particle size of the emulsion and microcapsules when producing microcapsules according to the present invention.

FIG. 4 shows an example of the relationship between the concentration of the film-forming polymer and the particle size of the emulsion and microcapsules when producing microcapsules according to the present invention.

FIG. 5 shows an example of the relationship between the concentration of a core substance and the particle size of an emulsion and microcapsules when producing microcapsules according to the present invention.

FIG. 6 shows an example of the relationship between the concentration of the film-forming polymer and the sustained release rate of the microcapsules when producing microcapsules according to the present invention.

FIG. 7 shows an example of the relationship between the concentration of a surfactant and the sustained release rate of microcapsules when producing microcapsules according to the present invention.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Koichiro Shiomori 1-1 Gakuen Kihanadai Nishi, Miyazaki City, Miyazaki Prefecture Miyazaki University F term (reference) 4C076 AA61 EE25 GG30 4G005 AA01 AB12 BA12 BB08 DA02X DB22X DD37Z EA02 EA03 4H011 AC01 AC03 BA01 BB17 BC18 BC19 DA06 DC11 DF02 DG05 DH06 DH18 DH29

Claims (4)

[Claims] 1. A core material having a desired activity, a porous core material carrier capable of adsorbing and retaining the core material, a hydrophobic film-forming polymer, and an organic solvent capable of dissolving the polymer. A step of preparing a first emulsion in which the core substance carrier having adsorbed and retained the substance is dispersed in the organic solvent in which the polymer is dissolved; adding the first emulsion to an aqueous solution to form the first emulsion; Preparing a second emulsion dispersed in water; and removing the organic solvent from the second emulsion and enclosing the core substance adsorbed and retained on the core substance carrier in a film made of the polymer. A method for producing microcapsules, comprising the step of obtaining microcapsules. 2. The method according to claim 1, wherein said core substance is adsorbed and retained from a core substance having a desired activity, a porous core substance carrier capable of adsorbing and retaining said core substance, a hydrophilic film-forming polymer, and water. Preparing a first emulsion in which the core substance carrier is dispersed in the water in which the polymer is dissolved; adding a second emulsion in which the first emulsion is added to an oil solution and the first emulsion is dispersed in the oil. Preparing an emulsion; and removing the water from the second emulsion to obtain microcapsules containing the core substance adsorbed and held on the core substance carrier in a film made of the polymer. A method for producing microcapsules, characterized in that: 3. The microcapsule according to claim 1, wherein Sumithion (registered trademark) is used as the core substance, activated carbon is used as the core substance carrier, poly-ε-caprolactam is used as the polymer, and ethyl acetate is used as the organic solvent. Manufacturing method. 4. A film made of poly-.epsilon.-caprolactam containing Sumithion having an encapsulation rate of 30% or more.
Sumithion-encapsulated biodegradable microcapsules having a particle size of m to 5 mm.