JPH057766A - Preparation of microcapsule - Google Patents

Abstract

PURPOSE:To simply, easily and economically prepare a microcapsule including vegetable essential oil excellent in stability with the elapse of time as a core substance. CONSTITUTION:Vegetable essential oil is added to a slurry obtained by mixing gum arabic, sugar fatty acid ester and water under stirring to form an emulsion. A solution consisting of castor oil and anhydrous ethanol held to low temp. is added to the obtained emulsion and a predetermined amount of anhydrous ethanol is further added to the resulting solution mixture and, hereinafter, a microcapsule including vagetable essential oil as a core substance is prepared according to a usual method.

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 having a core substance of natural or synthetic plant essential oil such as peppermint oil.

[0002]

2. Description of the Related Art A microcapsule is a container (capsule) in which microscopic units are enclosed, and various substances are contained therein. By destroying the capsule, the internal core substance is released or the encapsulated core substance is encapsulated. Since it can be used in a wide variety of ways, such as slowly releasing it, it has many usefulness.

[0003] In such microcapsules, a method for producing microcapsules containing a liquid core substance is roughly classified into a coacervation method and an interfacial precipitation method by precipitation at the interface of an emulsion. The coacervation method utilizes a phenomenon in which a polymer solution is phase-separated into a high-concentration phase and a low-concentration phase due to changes in the environment (addition of other substances, etc.). It is said that oils and powders that are insoluble in water can be easily microencapsulated, which is particularly advantageous.

[0004]

The inventor of the present invention is
In order to obtain microcapsules containing plant essential oils such as mackerel oil as a core substance, we tried microencapsulation by the coacervation method, which is advantageous for microencapsulation of oils. However, in the known coacervation method, it is extremely difficult to obtain microcapsules in an economically advantageous state, and even if microcapsules are obtained, the microcapsules themselves are aggregated with each other and easily disintegrated. There were many problems in practical use, such as being able to obtain only that.

In view of the present situation, the inventor has conducted an earnest study on microcapsules containing a plant essential oil as a core substance by an interfacial precipitation method, which is not so advantageous for microencapsulation of oils. The present invention has completed the method for producing microcapsules according to the present invention, which enables economical production of microcapsules containing a plant essential oil having excellent stability over time as a core substance.

[0006]

The method for producing microcapsules according to the present invention comprises preparing a slurry by mixing gum arabic, which is a coating substance, and a surfactant composed of sucrose fatty acid ester, with water to prepare a slurry. A core substance consisting of vegetable essential oil was added to the slurry to form an emulsion by stirring, and a mixed solution of castor oil and absolute ethanol was added to the emulsion to maintain the liquid at a low temperature while further adding an anhydrous solution to the mixed solution. Add ethanol,
The present invention is characterized in that a microcapsulated precipitate is produced by stirring, and the precipitate is dried to obtain microcapsules containing a plant essential oil as a core substance.

In the present invention, the plant essential oil constituting the core substance of the microcapsules is a fragrance obtained from natural products such as peppermint oil, orange oil, lemongrass oil, lavender oil, and other useful plant essential oils and these natural products. Essential oils obtained by synthesizing components contained in plant essential oils.

[0008] Gum arabic which is a coating substance and a surfactant made of sucrose fatty acid ester are mixed with water to prepare a slurry, and a core substance made of a plant essential oil is added to the obtained slurry to form by stirring. The emulsion is prepared by maintaining the liquid temperature at 35 ° C. or lower, more preferably 0 to 20 ° C. When the liquid temperature is 35 ° C. or higher, the plant essential oil may volatilize, which is not preferable.

When castor oil and absolute ethanol are added to the emulsion to form a microcapsule precipitate by stirring, the liquid temperature is 35 ° C. or lower, preferably 0 to
When the liquid temperature exceeds 35 ° C., arabic rubber which is a film-forming substance formed is in a softened state and cannot form a predetermined capsule, or the capsule is formed. However, the wall membrane is easily broken and the desired microcapsules cannot be obtained. On the other hand, when the liquid temperature is negative, the formation of capsules is not so hindered, but the solution itself tends to coagulate, which is not preferable.

The surfactant sucrose fatty acid ester is HLB (hydrophillipophile).
It is preferable to select and use those having a balance of 8 to 15, and those having a deviance from this range are difficult to proceed with encapsulation.

The absolute ethanol added to the mixed solution obtained by adding the mixed solution of castor oil and absolute ethanol to the emulsion is 3 times the amount of the mixed solution or more, more preferably 3 to 5 times.
If the amount is double and the amount is equal to or less than 3 times, uniform dispersion cannot be achieved, which is not preferable.

[0012]

The method for producing microcapsules of the present invention is based on the interfacial precipitation method. The general method for producing microcapsules by the interfacial precipitation method is the interfacial precipitation method in water using a [(W / O) / W] type composite emulsion, where W is water and O is oil. There is an interfacial precipitation method in oil using a (O / W) / O] type composite emulsion. This invention adopts the latter [(O / W) / O] type method, and comprises an oil phase (O) containing a plant essential oil as a core substance in a dissolved state, and a film having a film forming ability. An oil-in-water type, that is, an (O / W) type emulsion is formed with the aqueous phase (W) in which the substance is dissolved, and this emulsion is dispersed in another oil-based solution (O) that is an encapsulating medium. (O / W) / O] type composite emulsion is produced.
O] type composite emulsions are used to form microcapsules.

In this case, gum arabic is used as the coating material, sucrose fatty acid ester having an HLB of 8 to 15 is used as a surfactant, and castor oil is used as the other oil-based solution to form an emulsion, and anhydrous ethanol is used. The microcapsules are formed as a precipitate from this emulsion in the presence of. By carrying out such a precipitation-forming operation at a liquid temperature of 20 ° C. or lower, the finally obtained microcapsules have a core of a plant essential oil in which a reliable film-forming is formed without the capsules adhering to each other. Microcapsules can be obtained.

[0014]

EXAMPLES Hereinafter, examples of production of microcapsules containing peppermint oil as a core substance according to the method for producing microcapsules of the present invention will be described in detail by showing examples and comparative examples.

Example 1 50 g of gum arabic, 5 g of sucrose fatty acid ester of HLB11 and 40 g of water were mixed with a homomixer to obtain about 10,
The mixture was stirred at 000 rpm to form a homogeneous slurry mixture, which was cooled to a temperature of 10 ° C or lower. To this mixture, 25 g of peppermint oil was added, and the mixture was stirred with a homomixer until a uniformly dispersed emulsified state was obtained to form an emulsion. Furthermore, after adding 150 g of castor oil and 125 g of anhydrous ethanol to a mixed solution having a liquid temperature of 5 ° C., the mixture was added to the above emulsion and stirred with a homomixer until a uniform dispersion liquid was obtained. 1 liter of absolute ethanol was added thereto, and the mixture was stirred with a homomixer for about 5 minutes. The supernatant of the obtained liquid was removed by decantation, the precipitate was filtered off, and the produced capsule was taken out. The capsules were dried under reduced pressure to completely remove the solvent to obtain about 90 g of powdery microcapsules. The microcapsules thus obtained are multi-core single-coated capsules in which peppermint oil is used as a core substance and gum arabic as a coating substance and the coating substances do not adhere to each other, and have sustained release properties and stability over time. Was good.

Example 2 50 g of gum arabic, 5 g of sucrose fatty acid ester of HLB13 and 40 g of water were mixed with a homomixer to obtain about 10,
The mixture was stirred at 000 rpm to form a homogeneous slurry mixture, which was cooled to a temperature of 10 ° C or lower. To this mixture, 25 g of peppermint oil was added, and the mixture was stirred with a homomixer until a uniformly dispersed emulsified state was obtained to form an emulsion. Further, 150 g of castor oil and 125 g of absolute ethanol cooled to a temperature of 5 ° C. were added to the above emulsion and stirred with a homomixer until a uniform dispersion liquid was obtained. 1 liter of absolute ethanol was added and stirred with a homomixer for about 5 minutes. The supernatant of the obtained liquid was removed by decantation, the precipitate was filtered off, and the produced capsule was taken out. The capsules were dried under reduced pressure to completely remove the solvent to obtain about 80 g of powdery microcapsules. The microcapsules thus obtained are multi-core single-coated capsules in which peppermint oil is used as a core substance and gum arabic as a coating substance and the coating substances do not adhere to each other. Was good.

Comparative Example 1 Mint oil was microencapsulated by the coacervation method as follows. First, 10 g of a 4% gelatin aqueous solution having a jelly strength of 202 g, 1 g of a 10% aqueous solution of gum arabic and 5 g of peppermint oil were mixed, and the mixture was stirred and heated to a temperature of 45 ° C. At a temperature of 42 ° C., 3 g of a 3% Na ₂ SO ₄ aqueous solution was added to this mixed liquid, and then the liquid temperature was lowered to 36 ° C.
g was added. Furthermore, the liquid temperature of this liquid is cooled to 9 ° C., and 10% alum (potassium aluminum sulfate) is added.
1.5 g was added, formation of capsules was confirmed, and the liquid temperature was gradually returned to room temperature. By this operation, microcapsules with mint oil as the core substance and gelatin as the coating substance were produced, but when the obtained microcapsules were separated from the liquid phase by filtration, the microcapsules themselves aggregated, When left at room temperature, the capsules collapsed and the desired powdery microcapsules could not be obtained.

[0018]

Industrial Applicability In the method for producing microcapsules of the present invention, gum arabic is used as a film substance and sucrose fatty acid ester is mixed as a surfactant in water to prepare a slurry, and the obtained slurry is composed of plant essential oil. Add core material,
After stirring to form an emulsion, add a mixed solution of castor oil and absolute ethanol to the emulsion to keep it at a low temperature, and add a predetermined amount of absolute ethanol to the cold mixed solution to core the plant essential oil. The microcapsules used as the substance can be manufactured easily, easily and economically. In particular, it is excellent in that microcapsules having a strong film structure can be easily obtained by controlling the liquid temperature of the mixed solution.

The microcapsules obtained by the method of the present invention are excellent in stability over time, and can release the plant essential oil in the interior by breaking the capsule or release the plant essential oil through the capsule. , The usefulness of plant essential oils can be expanded.

Claims (5)

[Claims] 1. A coating substance, gum arabic, and a surfactant made of sucrose fatty acid ester are mixed with water to prepare a slurry, and a core substance made of plant essential oil is added to the obtained slurry and stirred. While forming an emulsion by adding a mixed solution of castor oil and absolute ethanol to this emulsion, maintaining the liquid at a low temperature,
Anhydrous ethanol was further added to this mixed solution to generate a microencapsulated precipitate by stirring, and the precipitate was dried to obtain a microcapsule containing plant essential oil as a core substance. Production method. 2. The formation of the emulsion is performed at a liquid temperature of 35.
The method for producing a microcapsule according to claim 1, wherein the method is carried out at a temperature of not higher than 0 ° C. 3. The method for producing microcapsules according to claim 1, wherein the mixed solution of castor oil and absolute ethanol has a liquid temperature of 35 ° C. or lower. 4. The method for producing microcapsules according to claim 1, wherein the sucrose fatty acid ester surfactant has an HLB of 8 to 15. 5. The method for producing microcapsules according to claim 1, wherein the absolute ethanol added to the mixed solution is 3 to 5 times as much as the mixed solution.