Method for preparing multilayer lamellar liquid crystal emulsion including intercellular lipids

Abstract

A method for preparing a liquid crystal emulsion includes: a) mixing, warming and dissolving intercellular lipid ingredients, non-polyoxyethylene (POE) based non-ionic surfactant, higher fatty alcohol, oil and wax to provide an oil phase part; b) mixing, warming and dissolving water, polyol and the other aqueous phase ingredients to provide an aqueous phase part; c) adding the oil phase part to the aqueous phase part, followed by agitation; d) introducing a viscosity modifier to the mixture solution under agitation; e) subjecting the mixture solution to rapid cooling under vacuum while carrying out debubbling under vacuum; and f) filtering the mixture solution through a filtering paper or filtering cloth. Provided is a stable liquid crystal emulsion having a multilayer lamellar structure including a large amount of intercellular lipid ingredients through a process using rapid cooling. The liquid crystal emulsion has an oil phase part and an aqueous phase part.

Claims

1. A method for preparing a liquid crystal emulsion, comprising the steps of: a) mixing, warming and dissolving intercellular lipid ingredients, non-polyoxyethylene (POE) based non-ionic surfactant, higher fatty alcohol, oil and wax to provide an oil phase part; b) mixing, warming and dissolving water, polyol and aqueous phase ingredients to provide an aqueous phase part; c) adding the oil phase part to the aqueous phase part, followed by agitation, to form a mixture solution; d) introducing a viscosity modifier to the mixture solution, while agitating the mixture solution, to form a modified mixture solution; e) subjecting the modified mixture solution to rapid cooling under vacuum, while carrying out debubbling under vacuum, to form a rapid-cooled mixture solution; and f) filtering the rapid-cooled mixture solution through a filtering paper or a filtering cloth, wherein the non-polyoxyethylene (POE) based non-ionic surfactant in the step (a) is a mixture of lecithin, sorbitan-based surfactants, and glucoside-based surfactants.

2. The method for preparing a liquid crystal emulsion according to claim 1, wherein the intercellular lipids include ceramides, cholesterol, phytosphingosine, triglycerides and free fatty acids.

3. The method for preparing a liquid crystal emulsion according to claim 1, wherein the lecithin is used in an amount of 0.05-1 wt %, the sorbitan-based surfactant is used in an amount of 0.1-5 wt %, and the glucoside-based surfactant is used in an amount of 0.1-5 wt %, based on a total weight of the liquid crystal emulsion.

4. The method for preparing a liquid crystal emulsion according to claim 1, wherein the polyol is at least one selected from the group consisting of glycerin, propylene glycol, dipropylene glycol, 1,3-butylene glycol, pentylene glycol, 1,2-octanediol and 1,2-hexanediol.

5. The method for preparing a liquid crystal emulsion according to claim 1, wherein the rapid cooling is carried out from 70 C.-90 C. to 40-50 C. within 5-15 minutes after forming the modified mixture solution.

6. The method for preparing a liquid crystal emulsion according to claim 1, wherein the liquid crystal emulsion has a multilayer lamellar structure.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is an image of the liquid crystal emulsion according to an embodiment observed by a polarization microscope at different temperatures, wherein the Maltose cross pattern unique to a multilayer lamellar structure can be observed by a polarization microscope starting from about 45 C. (a: 73 C., b: 63 C., c: 53 C., d: 45 C., e: 35 C., f: 25 C.).

(2) FIG. 2 is an image illustrating a difference in particles as a function of cooling rate of liquid crystal emulsion, as taken by a polarization microscope.

(3) FIG. 3 is an image illustrating liquid crystal emulsions obtained by using different types of surfactants, as taken by a polarization microscope (a: lecithin, b: sorbitan-based surfactant, c: glucoside-based surfactant, d: combination of surfactants a)-c)).

(4) FIG. 4 is an electron microscopic image illustrating the multilayer lamellar structure of the liquid crystal emulsion according to the present disclosure (left: liquid crystal emulsion having a multilayer lamellar structure, right: magnified view of a multilayer lamellar structure).

BEST MODE

(5) Exemplary embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth therein.

Test Example 1: Test for Determining Stability Depending on Surfactant

(6) TABLE-US-00001 TABLE 1 Comp. Comp. Comp. Ingredients Ex. 1 Ex. 2 Ex. 3 Ex. 1 1. Vegetable wax 0.5 0.5 0.5 0.5 2. Cetostearyl alcohol 2.0 2.0 2.0 2.0 3. Cholesterol 0.5 0.5 0.5 0.5 4. Ceramide-3 0.5 0.5 0.5 0.5 5. Stearic acid 1.0 1.0 1.0 1.0 6. Phytosphingosine 0.3 0.3 0.3 0.3 7. Behenyl alcohol 0.5 0.5 0.5 0.5 8. Lecithin 0.2 0.2 9. Sorbitan Palmitate 1 1 10. C12-20Alkyl Glucoside 1 1 11. Caprylic/capric triglyceride 10.0 10.0 10.0 10.0 12. Dimethicone 2.0 2.0 2.0 2.0 13. Cyclopentasiloxane 2.0 2.0 2.0 2.0 14. D.I. Water To 100 To 100 To 100 To 100 15. EDTA-2Na 2.0 2.0 2.0 2.0 16. Glycerin 7.0 7.0 7.0 7.0 17. Butylene Glycol 5.0 5.0 5.0 5.0 18. 1% Carbomer solution 15 15 15 15 19. Triethanolamine 0.12 0.12 0.12 0.12 20. Preservatives qsad qsad qsad qsad 21. Perfume 0.1 0.1 0.1 0.1

(7) <Preparation Method>

(8) 1) In Table 1, ingredients 3-6 are intercellular lipids, 8-10 are non-POE based non-ionic surfactants, 2 and 7 are higher fatty alcohols, 11-13 are oil, 1 is wax, 14-17 are water-soluble ingredients, wherein 16 and 17 are polyols, 18 and 19 are viscosity modifiers, 20 is a preservative, and 21 is a perfume ingredient.

(9) 2) In Table 1, ingredients 1-13 are mixed and dissolved at 70-80 C. to provide an oil phase solution.

(10) 3) In a separate container, ingredients 14-17 of Table 1 are mixed, and then warmed and dissolved to 70-80 C. to provide an aqueous phase solution.

(11) 4) The oil phase solution of 2) is added to the aqueous phase solution of 3), followed by agitation with a homomixer.

(12) 5) Then, ingredient 18 of Table 1 is mixed with the mixture solution obtained from 4), followed by mixing with ingredient 19.

(13) 6) Right after carrying out the process of 5), the reaction mixture is subjected to rapid cooling so that it is cooled to 40 C. within 10 minutes. Then, ingredients 20 and 21 of Table 1 are introduced and the reaction mixture is debubbled.

(14) Comparative Examples 1-3 and Example 1 obtained according to Table 1 are observed with a polarization microscope. As shown in FIG. 3, use of a combination of surfactants ((d) of FIG. 3) improves the stability of liquid crystals much more than use of a single surfactant alone ((a), (b), (c) of FIG. 3).

Test Example 2: Preparation of Comparative Examples and Example

(15) TABLE-US-00002 TABLE 2 Ingredients Amount (%) 1. Vegetable wax 0.5 2. Cetostearyl alcohol 2.0 3. Cholesterol 0.5 4. Ceramide-3 0.5 5. Stearic acid 1.0 6. Phytosphingosine 0.3 7. Behenyl alcohol 0.5 8. Lecithin 0.2 9. Sorbitan Palmitate 1 10. C12-20Alkyl Glucoside 1 11. Caprylic/capric triglyceride 10.0 12. Dimethicone 2.0 13. Cyclopentasiloxane 2.0 14. D.I. Water To 100 15. EDTA-2Na 2.0 16. Glycerin 7.0 17. Butylene Glycol 5.0 18. 1% Carbomer solution 15 19. Triethanolamine 0.12 20. Preservatives qsad 21. Perfume 0.1

(16) <Preparation Method>

(17) 1) In Table 2, ingredients 3-6 are intercellular lipids, 8-10 are non-POE based non-ionic surfactants, 2 and 7 are higher fatty alcohols, 11-13 are oil, 1 is wax, 14-17 are water-soluble ingredients, wherein 16 and 17 are polyols, 18 and 19 are viscosity modifiers, 20 is a preservative, and 21 is a perfume ingredient.

(18) 2) In Table 2, ingredients 1-13 are mixed and dissolved at 70-80 C. to provide an oil phase solution.

(19) 3) In a separate container, ingredients 14-17 of Table 2 are mixed, and then warmed and dissolved to 70-80 C. to provide an aqueous phase solution.

(20) 4) The oil phase solution of 2) is added to the aqueous phase solution of 3), followed by agitation with a homomixer.

(21) 5) Then, ingredient 18 of Table 2 is mixed with the mixture solution obtained from 4), followed by mixing with ingredient 19 of Table 2.

(22) 6) In Example 1, right after carrying out the process of 5), the reaction mixture is subjected to rapid cooling so that it is cooled to 40 C. within 10 minutes. Then, ingredients 20 and 21 of Table 2 are introduced and the reaction mixture is debubbled (Example 1 in Test Example 2 is the same as Example 1 in Test Example 1).

(23) 7) In Comparative Example 4, after carrying out the process of 5), the reaction mixture is allowed to stand at room temperature and then ingredients 20 and 21 of Table 2 are introduced thereto, followed by debubbling.

(24) Example 1 and Comparative Example 4 obtained according to Table 2 are observed with a polarization microscope. As shown in FIG. 2, a rapid cooling process provides a liquid crystal emulsion having higher stability as compared to a slow cooling process.

Test Example 3: Test for Determining Stability of Liquid Crystal Emulsion Particles Depending on Cooling Rate

(25) Example 1 and Comparative Example 4 are observed for the state of liquid crystal emulsion particles depending on temperature by using a polarization microscope. In this manner, the particle size, density and stability of the liquid crystal emulsion according to each of Example 1 and Comparative Example 4 are determined.

(26) After the observation, as shown in FIG. 2, a rapid cooling process allows higher fatty alcohols to undergo a transition from a liquid phase to a liquid crystal phase at about 40-45 C. while they are oriented well at the interface, thereby forming liquid crystal emulsion particles having a size of 5-15 m. On the contrary, a slow cooling process causes higher fatty alcohols to move from an oil phase (dispersion phase) to an aqueous phase (continuous phase), resulting in collapse of liquid crystal array. Thus, as shown in FIG. 2, it can be seen that the number of liquid crystal emulsion particles forming a multilayer lamellar structure is small and the density of multilayer lamellar structure is lower as compared to a rapid cooling process.

(27) In addition, to determine stability of a liquid crystal emulsion in Example 1 and Comparative Example 4 depending on temperature, each composition is tested for its stability under the conditions of refrigeration (18 C.), cooling (4 C.), room temperature, 37 C., 45 C. and in a CYC (12 hours for each of the conditions of refrigeration, room temperature and 45 C.) thermostat for 3 months. The results are shown in the following Table 3.

(28) TABLE-US-00003 TABLE 3 Room Refrigeration Cooling Temper- (18 C.) (4 C.) ature 37 C. 45 C. CYC Ex. 1 Stable Stable Stable Stable Stable Stable Comp. Stable Stable Unstable Unstable Liquid Unstable Ex. 4 crystal weakened

(29) As shown in FIG. 3, the liquid crystal emulsion (Example 1) obtained through a rapid cooling process shows a stable multilayer lamellar structure for 3 months under all temperature conditions. However, it is shown that the liquid crystal emulsion (Comparative Example 4) obtained through a slow cooling process causes weakening of liquid crystals or collapse of liquid crystals and an increase in viscosity under the storage conditions of room temperature, 37 C., 45 C. and under a thermoset storage condition.

Test Example 4: Test for Stability of Intercellular Lipid Ingredients in Formulation

(30) To determine the stability of intercellular lipid ingredients in a formulation, a conventional emulsion and a liquid crystal emulsion are prepared. The conventional emulsion is prepared by excluding ingredients 1 and 6 from Test Example 2, and the liquid crystal emulsion is Example 1 in Test Example 2. The prepared conventional emulsion and liquid crystal emulsion are designated as Comparative Example 5 and Example 1, respectively. The stability of intercellular lipids in a formulation is determined based on a change in viscosity under the conditions of refrigeration, cooling, room temperature and high temperature. Measurement is carried out with a viscometer (Brookfield, DV-1 prime, USA) at room temperature (25 C.) by using spindle No. 64 under the conditions of 30 rpm. Measurement of viscosity is in the unit of cp. Right after the preparation of emulsion and after the lapse of 3 months, the viscosity under each of the storage conditions in a thermostat is listed in the following Table 4.

(31) TABLE-US-00004 TABLE 4 Room Refrigeration Cooling temperature 45 C. CYC Right Right Right Right Right after After 3 after After 3 after After 3 after After 3 after After 3 preparation months preparation months preparation months preparation months preparation months Ex. 1 9,500 10,000 9,500 10,500 9,500 10,700 9,500 11,000 9,500 10,900 Comp. 6,500 10,000 6,500 12,000 6,500 Non- 6,500 Non- 6,500 Non- Ex. 5 detectable detectable detectable

(32) As shown in Table 4, the liquid crystal emulsion (Example 1) shows an insignificant change in viscosity of 1,000-1,500 cp right after its preparation and after the lapse of 3 months. On the contrary, the conventional emulsion (Comparative Example 5) causes a change in viscosity of 3,500 cp or more under the conditions of refrigeration and cooling right after its preparation and after the lapse of 3 months. Particularly, under the room temperature and high-temperature storage conditions, a rapid increase in viscosity occurs, and thus viscosity cannot be determined.

Test Example 5: Test for Skin Safety of Liquid Crystal Emulsion

(33) Example 1 and Comparative Example 4 are evaluated for a skin irritation degree when applied to ten male and female adults not suffering from skin diseases as subjects. First, 20 L of each sample is applied to the forearm of each subject. Next, the test site is sealed and is allowed to be covered with a patch for 24 hours. After removing the patch, the reaction on the skin after 30 minutes and 24 hours is examined based on the terminology suggested in the CTFA (Cosmetic, Toiletry and Fragrance Association) Guideline. The evaluation criteria are as follows. The grades obtained from the subjects according to the evaluation criteria are averaged, and then evaluated as low irritative (average<1), slightly irritative (average<3), moderately irritative (average<5) and highly irritative (average 5).

(34) TABLE-US-00005 TABLE 5 Test Item Ex. 1 Comp. Ex. 4 Skin irritation index (PII) Non-irritative Non-irritative

(35) After the test, as can be seen from Table 5, the liquid crystal emulsion having a multilayer lamellar structure including intercellular lipids according to each of Example 1 and Comparative Example 4 causes no irritation, and thus can be used safely for commercial products.