NATURALLY DEGRADABLE MICROCAPSULES AND A METHOD OF PREPARING THE SAME

Abstract

The present invention relates to a method of preparing microcapsules, and the microcapsules prepared according to the preparation method of the present invention can exhibit high versatility, natural degradability and long-term stability, and the active substance in the capsule can be stably loaded in the capsule even in the presence of a surfactant.

Claims

1-25. (canceled)

26. A method of preparing microcapsules, comprising: preparing a Pickering emulsion by mixing a continuous phase 1 comprising inorganic particles and a first encapsulating component, and a dispersed phase 1 including a second encapsulating component and a first capsule reinforcing component; and mixing and encapsulating a continuous phase 2 comprising a second capsule reinforcing component and the Pickering emulsion; wherein the first encapsulating component and the second encapsulating component each comprise an amine group or a hydroxyl group; the second encapsulating component and the first capsule reinforcing component are each a compound comprising two or more functional groups selected from the group consisting of an amine group, an isocyanate group, an acyl halide group, a chloroformate group and an acrylate group; an oligomer using the compound as a monomer; or a polymer using the compound as a monomer.

27. The method of claim 26, further comprising adsorbing natural degradation promoting particles to the capsule.

28. The method of claim 26, wherein the first encapsulating component is a biodegradable polymer.

29. The method of claim 26, wherein the second encapsulating component is a compound represented by the following Chemical Formula 1: ##STR00005## In Chemical Formula 1, R.sub.1 is an acrylate group or an alkylene group having 1 to 50 carbon atoms in which a hetero atom is substituted or unsubstituted; a cyclic hydrocarbon having 3 to 60 carbon atoms; or a compound comprising an alkylene group having 1 to 50 carbon atoms and a cyclic hydrocarbon having 3 to 60 carbon atoms, X.sub.1 to X.sub.4 are each independently selected from the group consisting of hydrogen, an amine group, an acyl halide group, an isocyanate group, a chloroformate group and an acrylate group, n is an integer greater than or equal to 1.

30. The method of claim 26, wherein when the first encapsulating component and the second capsule reinforcing component have amine groups, the second encapsulating component and the first capsule reinforcing component have acrylate groups or isocyanate groups.

31. The method of claim 26, wherein when the first encapsulating component and the second capsule reinforcing component have hydroxyl groups, the second encapsulating component and the first capsule reinforcing component have isocyanate groups, acyl halide groups, chloroformate groups or acrylate groups.

32. The method of claim 26, wherein the first capsule reinforcing component is one or more compounds selected from the group consisting of a monomer represented by the following Chemical Formula 2, methylenediphenyl diisocyanate, naphthalene diisocyanate, and isophorone diisocyanate; an oligomer thereof; or a polymer thereof: ##STR00006## In Chemical Formula 2, R.sub.2 to R.sub.7 each independently comprise hydrogen; an alkyl group having 1 to 5 carbon atoms; an alkenyl group having 2 to 5 carbon atoms; an alkyl isocyanate having 1 to 5 carbon atoms; an isocyanate group; an alkylacyl halide group having 1 to 5 carbon atoms; an acyl halide group; an alkylchloroformate group having 1 to 5 carbon atoms; a chloroformate group; an alkyl acrylate group having 1 to 5 carbon atoms; or an acrylate group; one or more of R.sub.2 to R.sub.7 in Chemical Formula 2 is a compound comprising one of an isocyanate group, an acyl halide group, a chloroformate group, and an acrylate group.

33. The method of claim 26, wherein the second capsule reinforcing component is one or more compounds selected from the group consisting of a monomer represented by the following Chemical Formula 3, melamine, and benzidinedisulfonic acid; an oligomer thereof; or a polymer thereof: ##STR00007## In Chemical Formula 3, R.sub.8 to R.sub.13 each independently comprise hydrogen; an amine group; a hydroxyl group; an alkyl group having 1 to 5 carbon atoms; an alkylamine group having 1 to 5 carbon atoms; a hydroxyalkyl group having 1 to 5 carbon atoms; or an alkenyl group having 2 to 5 carbon atoms; one or more of R.sub.8 to R.sub.13 in Chemical Formula 3 is a compound comprising either an amine group or a hydroxyl group.

34. The method of claim 26, wherein the Pickering emulsion further comprises a capsule reinforcing inorganic precursor.

35. The method of claim 34, wherein the capsule reinforcing inorganic precursor is a compound represented by the following Chemical Formula 4: ##STR00008## In Chemical Formula 4, R.sub.14 to R.sub.17 are each independently hydrogen; an alkoxy group having 1 to 5 carbon atoms; an alkyl group having 1 to 5 carbon atoms; or a hydrocarbon compound having 1 to 5 carbon atoms comprising one or more functional groups selected from the group consisting of an amine group, a thiol group, a hydroxyl group, a carbonyl group, a carboxyl group, and an ether group.

36. The method of claim 27, wherein the natural degradation promoting particles are selected from the group consisting of titanium oxide, zinc oxide, zirconium oxide, tungsten oxide, platinum, platinum oxide, and gold chloride.

37. The method of claim 26, wherein the Pickering emulsion comprises an active substance selected from the group consisting of fragrance oils, sunscreens, dyes, catalysts, antioxidants and drugs.

38. A microcapsule prepared according to the method of claim 26.

39. A fabric softener composition comprising the microcapsule of claim 38.

40. A microcapsule comprising a first encapsulating component, a second encapsulating component, a first capsule reinforcing component, a second capsule reinforcing component, and inorganic particles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0095] FIG. 1 is a schematic diagram of a method of preparing a microcapsule according to the present invention.

[0096] FIG. 2 is a comparison of performance/stability in the presence of a surfactant after storing the microcapsules according to the present invention at 50° C. for 7 days.

[0097] FIG. 3 shows the results of confirming the degree of acceleration of degradation of microcapsules according to the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0098] Hereinafter, the present invention will be described in detail by way of Examples. The following Examples merely illustrate the present invention but do not limit the scope of the present invention.

[0099] Materials and reagents used in Examples and Comparative Examples were purchased and used from cosmetic raw material manufacturers and commercial suppliers, and the indicated content is based on weight %.

Examples 1-6. Preparation of Polyurea Microcapsules

[0100] Microcapsules were prepared according to the compositions of Table 1 below. First, 1 g of silica was dispersed in 68 g of distilled water and at the same time 1 g of the first encapsulating component (hereinafter referred to as a biodegradable polymer) which is a biodegradable polymer corresponding to each of Examples 1 to 6 was added to prepare a continuous phase 1. 0.5 g of polyisocyanate as the second encapsulating component was added to 29.5 g of dodecane to prepare a dispersed phase. Then, the dispersed phase was added to continuous phase 1 and stirred at 2,000 rpm to prepare a Pickering emulsion. Thereafter, the Pickering emulsion was subjected to interfacial polymerization at 80° C. for 12 hours to prepare polyurea microcapsules.

Comparative Examples 1 and 2. Preparation of Polyurea Microcapsules

[0101] Polyurea microcapsules of Comparative Examples 1 and 2 were prepared according to the compositions of Table 1 below. First, 1 g of polyethyleneimine was dissolved in 69 g of distilled water, and then a polymerization reaction was conducted at 80° C. for 12 hours while mixing a solution of 0.5 g of polyisocyanate in 29.5 g of dodecane to prepare the polyurea microcapsules of Comparative Example 1.

[0102] Next, 1 g of silica was dispersed in 68 g of distilled water and 1 g of polyethyleneimine was added thereto to prepare a continuous phase 1. 0.5 g of polyisocyanate was added to 29.5 g of dodecane to prepare a dispersed phase. Then, the dispersed phase was added to continuous phase 1 and a Pickering emulsion was prepared at 2,000 rpm. Thereafter, the Pickering emulsion was subjected to interfacial polymerization at 80° C. for 12 hours to prepare polyurea microcapsules of Comparative Example 2.

Experimental Example 1. Comparison of Degree of Biodegradation of Microcapsules Including Biodegradable Polymers

[0103] The biodegradability of the microcapsules prepared in Examples 1 to 6 and Comparative Examples 1 and 2 was compared. In this experimental example, biodegradability of microcapsules was measured using the OECD 301D method after the capsule wall was extracted. Specifically, the OECD 301D method is a test method for measuring dissolved oxygen consumption using an airtight test bottle, and is a method for measuring the biodegradability of capsules, which is a water-insoluble test substance, and the degree of biodegradation was calculated by the following General Formula 1 by measuring the biochemical oxygen demand (BOD) over time with respect to the theoretical oxygen demand (ThOD).

[00001]$\begin{array}{cc}\mathrm{Degree}\mathrm{of}\mathrm{Biodegradation}\left(\%\right)=\frac{\mathrm{BOD}}{ThOD}\times 100& \left[\mathrm{General}\mathrm{Formula}1\right]\end{array}$

TABLE-US-00001 TABLE 1 Com. Com. Ex. Ex. Ex. Ex. Ex. 1 Ex. 2 1 2 3 Ex. 4 Ex. 5 6 Distilled water 69 68 68 68 68 68 68 68 Silica — 1 1 1 1 1 1 1 Polyethyleneimine 1 1 — — — — — — Chitosan — — 1 — — — — — Polylysine — — — 1 — — — — Gelatin — — — — 1 — — — Silk fibroin — — — — — 1 — — Hydrolyzed — — — — — — 1 — keratin Poly(2-acrylamido — — — — — — — 1 glycolicacid (PAGA) Polyisocyanate 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Dodecane 29.5 29.5 29.5 29.5 29.5 29.5 29.5 29.5 Total 100 100 100 100 100 100 100 100 Degree of 20 20 55 40 80 45 50 50 biodegradation (%)

[0104] As a result of measuring the degree of biodegradation of the microcapsules according to the inclusion of the biodegradable polymer (Table 1), all of the encapsulation reactions occurred except for Comparative Example 1, which did not form a Pickering emulsion, and microcapsules of Examples 1 to 6 made of chitosan, polylysine, gelatin, silk fibroin, keratin, or PAGA as a natural biodegradable polymer showed relatively higher biodegradability than polyethyleneimine as the synthetic polymer.

Examples 7 to 9. Preparation of Polyurea Microcapsules

[0105] Polyurea microcapsules were prepared according to the compositions of Table 2 below. First, 1 g of silica was dispersed in 58 g of distilled water, and 1 g of chitosan as a biodegradable polymer (first encapsulating component) was added to prepare a continuous phase 1, and 1 g of phenylenediamine as a second capsule reinforcing component was added to 9 g of distilled water to prepare a continuous phase 2. To 29.5 g of fragrance oil, 0.5 g of a combination of polyisocyanate as a second encapsulating component, and methyldiphenyldiisocyanate as a first capsule reinforcing component was added to prepare a dispersed phase. Then, the dispersed phase was added to continuous phase 1 and stirred at 2,000 rpm to prepare a Pickering emulsion. Thereafter, continuous phase 2 was added to the Pickering emulsion, and interfacial polymerization was performed at 80° C. for 12 hours to prepare polyurea microcapsules.

Comparative Examples 3 to 7. Preparation of Polyurea Microcapsules

[0106] Microcapsules were prepared according to the compositions of Table 2 below. The microcapsules of Comparative Example 3 were prepared in the same manner as in Examples 1 to 6, except that polyisocyanate as the second encapsulating component was not included, and Comparative Examples 4 to 6 did not include a biodegradable polymer.

Experimental Example 2. Comparison of Stability and Degree of Biodegradation of Microcapsules Including Capsule Reinforcing Components

[0107] The stability and biodegradability of the microcapsules prepared in Examples 7 to 9 were confirmed. In this experimental example, stability is a measure of the ability of the capsule to retain the fragrance oil in the capsule even in a harsh environment in which the surrounding environment is surrounded by an emulsifier. Specifically, the stability was compared by adding 1 part by weight of microcapsules to 5 parts by weight of an aqueous Tween 20 solution, based on 100 parts by total weight of the composition, and after storage at 50° C. for 7 days, extracting perfume oil in capsules using ethanol and a tip sonicator (Fisherbrand™, Fisher Scientific, USA), and measuring the content thereof with a UV spectrometer (FastTrack™ UV Vis Technology, Mettler Toledo, USA). Biodegradability was measured in the same manner as in Experimental Example 1.

TABLE-US-00002 TABLE 2 Com. Com. Ex. Com. Ex. 1 Com. Ex. 3 Ex. 7 Com. Ex. 4 Ex. 5 Ex. 6 8 Ex. 7 Ex. 9 Distilled water 68 68 68 68 68 68 68 68 68 Silica 1 1 1 1 1 1 1 1 1 Chitosan 1 1 1 — — — 0.5 0.5 0.5 Phenylenediamine — — — 1 1 1 0.5 0.5 0.5 Polyisocyanate 0.5 — 0.25 0.5 — 0.25 0.5 — 0.25 Methyl diphenyl — 0.5 0.25 — 0.5 0.25 — 0.5 0.25 diisocyanate Fragrance oil 29.5 29.5 29.5 29.5 29.5 29.5 29.5 29.5 29.5 Total 100 100 100 100 100 100 100 100 100 Stability (%) 0 5 15 0 5 0 20 10 60 Degree of 55 40 45 20 20 20 45 35 40 biodegradation (%)

[0108] As a result of the experiment, the microcapsules of Comparative Examples 4 to 6, which did not contain the biodegradable polymer, showed low biodegradability and stability, and the microcapsules of Comparative Examples 3, 5 and 7, which did not contain the second encapsulating component, exhibited low stability because the capsule wall was not densely formed. When the first capsule reinforcing component was used, it was also confirmed that the degree of biodegradation decreased according to the amount used. On the other hand, when the second encapsulating polymer and the second capsule reinforcing component were used in combination, the capsule wall was densely formed and it was confirmed that the stability of the capsule was improved.

Examples 10 to 18. Preparation of Polyurea Microcapsules

[0109] Polyurea microcapsules were prepared according to the compositions of Table 3 below. First, 1 g of silica was dispersed in 58 g of distilled water, and 1 g of chitosan as a biodegradable polymer was added to prepare a continuous phase 1, and g of a second capsule reinforcing component (phenylenediamine, aminobenzylamine and benzidinedisulfonic acid) was added to 9 g of distilled water to prepare a continuous phase 2. A dispersed phase was prepared by adding a second encapsulating component and a first capsule reinforcing component (methyldiphenyl diisocyanate, naphthalene diisocyanate, isophorone diisocyanate and xylene diisocyanate) to 29.5 g of fragrance oil. Then, the dispersed phase was added to continuous phase 1 and stirred at 2,000 rpm to prepare a Pickering emulsion. Thereafter, continuous phase 2 was added to the Pickering emulsion, and interfacial polymerization was performed at 80° C. for 12 hours to prepare polyurea microcapsules.

Experimental Example 3. Comparison of Stability of Microcapsules Including Capsule Reinforcing Components

[0110] The stability and degree of biodegradation of the microcapsules prepared in Examples 10 to 18 were compared. The stability and degree of biodegradation were measured in the same manner as in Experimental Example 2.

TABLE-US-00003 TABLE 3 Ex. Ex. Ex. Ex. Com. Ex. Ex. Ex. Ex. Ex. 10 11 12 13 Ex. 8 14 15 16 17 18 Distilled water 68 68 68 68 68 68 68 68 68 68 Silica 1 1 1 1 1 1 1 1 1 1 Chitosan 0.5 0.25 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Phenylenediamine 0.5 0.75 0.5 0.5 — — — 0.5 0.5 0.5 Cyclohexanediamine — — — — 0.5 — — — — — Aminobenzylamine — — — — — 0.5 — — — — Benzidinedisulfonic — — — — — — 0.5 — — — acid Polyisocyanate 0.25 0.25 0.125 0.375 0.25 0.25 0.25 0.25 0.25 0.25 Methyl 0.25 0.25 0.375 0.125 0.25 0.25 0.25 — — — diphenyl diisocyanate Naphthalene — — — — — — — 0.25 — — diisocyanate Isophorone — — — — — — — — 0.25 — diisocyanate Xylene — — — — — — — — — 0.25 diisocyanate Fragrance oil 29.5 29.5 29.5 29.5 29.5 29.5 29.5 29.5 29.5 29.5 Total 100 100 100 100 100 100 100 100 100 100 Stability(%) 60 55 50 40 25 55 40 55 50 55 Degree of 40 30 40 40 40 40 40 40 40 40 biodegradation (%) Natural degradation 76 68.5 70 64 55 73 64 73 70 73 (%)

[0111] As a result of the experiment, it could be confirmed that the second capsule reinforcing component used in combination with the biodegradable polymer as the first encapsulating polymer exhibits excellent biodegradability and stability even when aminobenzylamine and benzidinedisulfonic acid are used in addition to phenylenediamine. In addition, the use of naphthalene diisocyanate, isophorone diisocyanate and xylene diisocyanate as well as methyldiphenyl diisocyanate as the first capsule reinforcing component used in combination with the second encapsulating component showed a good degree of biodegradation and stability. Accordingly, when the microcapsule according to the present invention uses a combination of the first encapsulating component (biodegradable polymer) and the second capsule reinforcing component, and a combination of the second encapsulating component and the first capsule reinforcing component, it can show a remarkable effect in the stability and degree of biodegradation.

[0112] On the other hand, in the case of Comparative Example 8, the stability of microcapsule was shown to be relatively very low. This is the result of Comparative Example 8 using cyclohexanediamine, a simple cyclic compound, not an aromatic compound, as the second capsule reinforcement component, for the preparation of microcapsules, and through this, it is shown that aromatic compounds, not simple cyclic compounds, are essential for the stability of the microcapsules.

Examples 19 to 22. Preparation of Polyurea Microcapsules

[0113] Microcapsules were prepared according to the compositions of Table 4 below. First, 1 g of silica was dispersed in 58 g of distilled water, and at the same time 1 g of chitosan as a biodegradable polymer was added to prepare a continuous phase 1, and 1 g of phenylenediamine as a second capsule reinforcing component was added to 9 g of distilled water to prepare a continuous phase 2. To 29.5 g of fragrance oil, a combination of polyisocyanate as a second encapsulating component, and methyldiphenyl isocyanate as a first capsule reinforcing component was added to prepare a dispersed phase. Then, the dispersed phase was added to continuous phase 1 and stirred at 2,000 rpm to prepare a Pickering emulsion. Then, a continuous phase 2 and capsule reinforcing inorganic precursors (tetraethyl orthosilicate, methyltrimethoxysilane, and aminopropyltrimethylethoxysilane) were added to the Pickering emulsion, and interfacial polymerization was performed at 80° C. for 12 hours to prepare polyurea microcapsules.

Experimental Example 4. Comparison of Stability and Degree of Biodegradation of Microcapsules Including Capsule Reinforcing Polymer

[0114] The stability and degree of biodegradation of the microcapsules prepared in Examples 19 to 24 were measured. Stability and the degree of biodegradation were measured in the same manner as in Experimental Example 2 above.

TABLE-US-00004 TABLE 4 Ex. Ex. Ex. Ex. Ex. 10 19 20 21 22 Distilled water 68 67.5 67 67.5 67 Silica 1 1 1 1 1 Chitosan 0.5 0.5 0.5 0.5 0.5 Phenylenediamine 0.5 0.5 0.5 0.5 0.5 Polyisocyanate 0.25 0.25 0.25 0.25 0.25 Methyl diphenyl 0.25 0.25 0.25 0.25 0.25 diisocyanate Tetraethy lorthosilicate — 0.5 1 — — Methyltrimethoxysilane — — — 0.5 1 Aminopropyltrimethylethoxysilane — — — — — Fragrance oil 29.5 29.5 29.5 29.5 29.5 Total 100 100 100 100 100 Stability(%) 60 80 70 75 65 Degree of biodegradation 40 40 40 40 40 (%)

[0115] As a result of the experiment, it was confirmed that the microcapsules of Examples 19 to 22 further including the capsule reinforcing inorganic precursor had increased stability compared to the microcapsules of Example 10 that did not include the capsule reinforcing inorganic precursor. However, it was confirmed that, as the content of the capsule reinforcing inorganic precursor increased, the microcapsule was easily broken during capsule preparation, and thus stability was rather decreased.

Examples 23 to 26. Preparation of Microcapsules

[0116] Microcapsules were prepared according to the compositions of Table 5 below. First, silica and biodegradation promoting particles (TiO.sub.2 and ZnO) were dispersed in 58 g of distilled water, and at the same time 1 g of chitosan as a biodegradable polymer was added to prepare a continuous phase 1, and 1 g of phenylenediamine as a second capsule reinforcing component was added to 9 g of distilled water to prepare a continuous phase 2. To 29.5 g of fragrance oil, a combination of polyisocyanate as a second encapsulating component, and methyldiphenyl diisocyanate as a first capsule reinforcing component was added to prepare a dispersed phase. Then, the dispersed phase was added to continuous phase 1 and stirred at 2,000 rpm to prepare a Pickering emulsion. Then, a continuous phase 2 and tetraethyl orthosilicate as a capsule reinforcing inorganic precursor were added to the Pickering emulsion, and interfacial polymerization was performed at 80° C. for 12 hours to prepare polyurea microcapsules.

Experimental Example 5. Confirmation of Biodegradability of Microcapsules Including Biodegradation Promoting Particles

[0117] The stability, biodegradability and photodegradability of the microcapsules prepared in Example above were measured. Stability and the degree of biodegradation were measured in the same manner as in Experimental Example 2 above, and photodegradability was measured with reference to the OECD 316 method. For the degradation measurement period, the energy corresponding to about 10,000 W/m.sup.2, which is equivalent to 4 weeks of average annual sunlight in Seoul, was irradiated using a xenon lamp using a sun tester (Suntest XLS+), and then the degree of degradation was measured by the following General Formula 2 by comparing the values before and after COD (Chemical Oxygen Demand).

[00002]$\begin{array}{cc}\mathrm{Degradation}\mathrm{rate}\left(\%\right)=\frac{\begin{array}{c}{\mathrm{COD}}_0-{\mathrm{COD}}_i\\ (\mathrm{Carbon}\mathrm{content}\mathrm{of}\\ \mathrm{the}\mathrm{substance}\mathrm{after}a\mathrm{certain}\\ \mathrm{period}\mathrm{of}\mathrm{time})\end{array}}{\begin{array}{c}{\mathrm{COD}}_0(\mathrm{Carbon}\mathrm{content}\mathrm{of}\\ 500\mathrm{ppm}\mathrm{of}\mathrm{substance})\end{array}}\times 100& \left[\mathrm{General}\mathrm{Formula}2\right]\end{array}$

[0118] According to the European Chemicals Agency (ECHA), it is not clearly defined according to the degree of degradation, but in the case of general biodegradability, it is classified as a degradable substance when it is degraded 20% or more and less than 60% by microorganisms for 4 weeks, and a substance that can be degraded immediately after being degraded 60% or more. Although degree of photodegradation has not yet been clearly defined, in the actual environment, all of microorganisms and sunlight, hydrolysis, pyrolysis, etc. are applied, and there is a need to consider the microorganisms and photodegradation as the two elements among them which may have the most influence.

TABLE-US-00005 TABLE 5 Ex. 19 Ex. 23 Ex. 24 Ex. 25 Ex. 26 Distilled water 67.5 67.5 67.5 67 67 Silica 1 0.5 0.5 1 1 Tio.sub.2 — 0.5 — 0.5 — ZnO — — 0.5 — 0.5 Chitosan 0.5 0.5 0.5 0.5 0.5 Phenylenediamine 0.5 0.5 0.5 0.5 0.5 Polyisocyanate 0.25 0.25 0.25 0.25 0.25 Methyl diphenyl 0.25 0.25 0.25 0.25 0.25 diisocyanate Tetraethylorthosilicate 0.5 0.5 0.5 0.5 0.5 Fragrance oil 29.5 29.5 29.5 29.5 29.5 Total 100 100 100 100 100 Stability (%) 80 80 80 80 80 Degree of biodegradation 40 40 40 40 40 (%) Photodegradation (%) 20 35 22 74 61 Natural degradability (%) 52 61 53.2 84.4 76.6

[0119] As a result of the experiment, in the case of Examples 23 to 26 including the biodegradation promoting particles, the addition of the biodegradation promoting particles did not significantly affect the stability and biodegradability of the capsule, but it was confirmed that the photodegradability was promoted.

Comparative Example 9. Preparation of Polyurea Microcapsules

[0120] Microcapsules were prepared according to the composition of Table 6 below. A continuous phase was prepared by dispersing Tween 20, arabic gum, and a pre-melamine formaldehyde solution in 54.5 g of distilled water. An emulsion was prepared by slowly adding 30 g of fragrance (dispersed phase) to the continuous phase at 2,000 rpm. After lowering to 1000 rpm, the pH was lowered to 5 with citric acid, and the capsule formation reaction was performed at 70° C. for 3 hours. After terminating the reaction by adjusting the pH to 7.5 using tromethamine, melamine-formaldehyde resin capsules were prepared by adding and adsorbing biodegradation promoting particles.

Comparative Example 10. Preparation of Polyurea Microcapsules

[0121] Microcapsules were prepared according to the composition of Table 6 below. A continuous phase was prepared by dissolving 0.5 g of polyvinyl alcohol in 63 g of distilled water. 1.8 g of methacrylic acid, 4 g of pentaerythritol triacrylate, and 0.2 g of 2,2′ azobis-(2-methylbutyronitrile) were dissolved in 30 g of fragrance to prepare a dispersed phase. The continuous phase was gradually added to the dispersed phase at 2,000 rpm to prepare an emulsion, and then the reaction was carried out at 80° C. for 6 hours to proceed with the capsule formation reaction, and biodegradation promoting particles were added and adsorbed to prepare an acrylic capsule.

Experimental Example 6. Measurement of Stability, Biodegradability and Photodegradability of Microcapsules

[0122] The stability, biodegradability and photodegradability of the microcapsules prepared in Examples above were measured. Stability, biodegradability and photodegradability were measured in the same manner as in Experimental Example 5 above.

TABLE-US-00006 TABLE 6 Com. Com. Ex. 25 Ex. 9 Ex. 10 distilled water 67 54 63 silica 1 — — TiO.sub.2 0.5 0.5 0.5 chitosan 0.5 — — phenylenediamine 0.5 — — polyisocyanate 0.25 — — methyl diphenyl diisocyanate 0.25 — — tetraethylorthosilicate 0.5 — — Tween 20 — 2 — Arabic gum — 5 — pre-melamine formaldehyde solution — 7.5 — tromethamine — 0.5 — Citric acid — 0.5 — Polyvinyl alcohol — — 0.5 Methacrylic acid — — 1.8 Pentaerytritol triacrylate — — 4 (2,2′ azobis-(2-methylbutyronitrile) — — 0.2 fragrance oil 29.5 30 30 Total 100 100 100 Stability (%) 80 90 85 Degree of biodegradation (%) 40 15 18 Photodegradation (%) 74 10 15 Natural degradability (%) 84.4 24 30.3

[0123] As a result of the experiment, in the case of a microcapsule including the first encapsulating component, the second encapsulating component, the first capsule reinforcing component and the second capsule reinforcing component as in the present invention, it was confirmed that it has higher biodegradability , photodegradability and natural degradability compared to Comparative Examples 9 and 10, which did not.

Experimental Example 7. Fragrance Intensity Evaluation After Washing

[0124] Washing evaluation was performed to confirm applicability as a fabric softener using the microcapsules prepared in Examples above. First, as for the test fiber, a commercially available cotton towel (30 cm×20 cm) was washed repeatedly in a washing machine 5 times using a standard amount of general laundry detergent, and then dehydrated. Based on 100 parts by total weight of the composition, 1 part by weight of previously prepared microcapsules was added into an aqueous solution including 5 parts by weight of Tween 20, and then the composition was stored at 50° C. for 7 days. After putting a standard amount of the composition (0.67 ml/L washing water) into a stirred washing machine, it was treated with a rinse course, and after dehydration, a cotton towel was taken out. Then, the cotton towel was dried for 12 hours at a humidity of 30% and a temperature of 25° C. At this time, three time points (immediately after washing, after drying and after rubbing) were set and 20 experienced panelists performed sensory evaluation to evaluate the fragrance intensity. Fragrance intensity was graded on a scale of a minimum of 0 points to a maximum of 5 points, based on 0 points for microcapsule-free cotton towels, and this was repeated three times or more and expressed as an average value. The sensory evaluation processed immediately after preparing the composition including the microcapsules and the sensory evaluation processed after the composition was stored for 7 days are shown in Table 7 and FIG. 2, respectively.

[0125] <Evaluation Criteria>

[0126] 0 points: There is hardly any fragrance left.

[0127] 5 points: There is a lot of fragrance left.

TABLE-US-00007 TABLE 7 Com. Ex. Ex. Ex. Ex. Ex. Ex. Ex. After 7 days Ex. 2 1 7 8 10 19 23 25 Immediately 1.21 1.81 1.34 1.31 1.2 1.13 1.08 1.27 after washing After drying 0.86 0.58 0.61 0.76 0.55 0.57 0.68 0.59 After friction 0.75 0.64 1.21 1.52 2.58 3.51 3.41 3.46

[0128] As shown in Table 7 and FIG. 2, in the case of Examples 7, 8, 10 and 19 including a biodegradable polymer, an encapsulating polymer, and a capsule reinforcing polymer, the capsule stability and fragrance diffusing properties were strongly exhibited, in particular, in the case of Example 19 in which the capsule reinforcing inorganic precursor was used, it was confirmed that the most excellent stability and fragrance diffusing properties were maintained. In addition, in the case of Examples 23 and 25 to which the natural degradation promoting particles were applied, it was confirmed that stability and fragrance diffusing properties similar to those of Example 19 were maintained. Through the above results, it was confirmed that the application of the natural degradation promoting particles did not affect the performance of the capsule.

Experimental Example 8. Confirmation of Degradation Promoting Effect

[0129] In order to confirm the degradation promoting effect of the microcapsules of the present invention, the capsules of Example 25 to which the natural degradation promoting particles were added were diluted in distilled water to a concentration of 500 ppm. Then, the degree of degradation in natural sunlight was compared using a particle size analyzer (Mastersizer 3000, Malvern) to measure the capsule size change over time. In order to confirm the degradation promoting effect, a transparent container, an opaque container, and a polypropylene container having an opaque wall surface (50 cm×50 cm×50) were filled with 100 L of water and the sample was filled to a depth of 15 cm in a specially prepared water-based condition, and then the container was fixed, and the degree of degradation by natural light was confirmed by the size change with time (FIG. 3).

[0130] As shown in FIG. 3, the capsule was degraded for 25 days by sunlight and reduced in size, and it was confirmed that the degradation of the capsule occurred even in water, but no degradation occurred in the opaque container, so there was no change in the size of the capsule. Through the above results, although the capsules are stably present in the form of a product, it can be confirmed that it means that degradation occurs when discharged into the natural world after use.