JP6019024B2 - High concentration emulsion - Google Patents

Description

  The present invention relates to a nanoemulsion that does not require a high shearing force, can be produced easily and inexpensively, has a high oil concentration, excellent stability, and high transmittance.

  The emulsion is a solution form used in a wide range of industrial fields, and the design of the composition and the preparation method is an important issue in order to obtain a stable emulsion. In general, an emulsion is a non-equilibrium system, and dispersed particles aggregate and coalesce with time, causing phase separation. Accordingly, various emulsification methods have been proposed in order to stabilize the emulsion.

  For example, in Patent Document 1, a predetermined amount of oil, higher alcohol, higher fatty acid, nonionic surfactant, water-soluble polyhydric alcohol and water is emulsified, and stirring conditions are selected, or a temperature shock or a stirring shock is applied to give a lamella. It discloses that a liquid crystal emulsion composition prepared by forming a structure (layered structure) is excellent in temperature stability and usability. However, in order to prepare the liquid crystal emulsion composition described in this document, a high shearing force is required, and thus it is necessary to process with a powerful emulsifier / stirrer.

  Patent Document 2 discloses a stable liquid crystal emulsion composition that can be produced without high shearing force. However, in order to prepare the liquid crystal emulsion composition described in the patent document, it is necessary to use a special hydrophilic surfactant.

  As described above, in order to obtain a stable emulsion having a high oil concentration and a small particle size, a large amount of energy is required, and treatment with a powerful emulsifier / stirrer that generally requires capital investment or an expensive emulsifier is used. Must be, not economical.

JP 2003-212716 A JP 2007-169214 A

  Therefore, an object of the present invention is to provide a nanoemulsion having a high oil concentration and excellent stability, which can be easily and inexpensively produced.

  In water-oil two-phase systems, emulsions with nano-sized dispersoids are thermodynamically stable compared to larger particle emulsions. For this reason, generally, preparation of such an emulsion requires a large amount of energy, and a powerful stirrer must be used. As described above, there is an economical problem.

  The present inventors have prepared a discontinuous cubic liquid crystal (Discontinuous Cubic) and diluted it with water or an aqueous solution containing a water-soluble additive, thereby exhibiting a transparent or translucent appearance. It was found that a nanoemulsion having a high viscosity and excellent stability can be prepared without using a special emulsifier or a strong shearing force.

  In addition, the emulsion prepared as described above was able to stably hold an oil component of about twice the weight ratio with respect to the amount of amphipathic molecules without causing phase separation. The solubilization limit (ie, inclusion ability) of the micelle solution prepared from amphiphilic molecules and water—for example, according to the face-centered cubic lattice packing model, all materials have a specific gravity of 1. Then, the oil concentration per total weight of the emulsion is calculated to be about 20% by weight-the characteristic of the emulsion of the present invention is clear.

  The present invention is based on the above findings and includes the following features.

  (1) An emulsion containing an amphiphilic molecule, water and an oil, wherein the emulsion includes a dispersoid that includes an oil that exceeds the solubilization limit amount of the amphiphilic molecule dispersed in a dispersion medium. And the said emulsion which shows the light transmittance of 70% or more by water solvent ratio, and the average particle diameter of this dispersoid is the range of 5-100 nm, The said emulsion characterized by the above-mentioned.

  (2) The emulsion according to (1) above, wherein the oil content is 2.0 times or less by weight with respect to the amphiphilic molecule content.

  (3) The emulsion according to (1) above, wherein the amphiphilic molecule is a nonionic surfactant.

  (4) The emulsion according to (1), further comprising a water-soluble additive.

  (5) The emulsion according to (4), wherein the water-soluble additive is at least one selected from the group consisting of polyhydric alcohols, inorganic salts, and water-soluble polymers.

  (6) A skin external preparation containing the emulsion according to any one of (1) to (5) above.

  (7) The external preparation for skin according to (6) above, wherein the external preparation for skin is cosmetic, or a quasi-drug or external pharmaceutical product for external use on the skin.

  (8) A pharmaceutical comprising the emulsion according to any one of (1) to (5) above.

  (9) A method for preparing an emulsion, the first step of preparing a discontinuous cubic liquid crystal containing an amphipathic molecule, water and oil, and the liquid crystal in water or a water-soluble additive And a second step of preparing a transparent or translucent aqueous solution by adding and diluting with an aqueous solution containing an oil component, wherein the oil content is less than twice the weight ratio to the amphiphilic molecule And said method.

  (10) The method according to (9), wherein the second step is performed under a shearing force of less than 3000 rpm at a stirring speed.

  According to the present invention, there is provided a nanoemulsion that has a high oil concentration and is excellent in stability, and can be easily and inexpensively produced.

FIG. 1 is a comparison of external views of an emulsion solution of the present invention (right) and an emulsion solution prepared by simply mixing components having the same composition as the emulsion solution of the present invention (left). FIG. 2 shows the change over time in the light transmittance of the emulsion when a shearing force of 3000 rpm, 4000 rpm and 5000 rpm is applied to the emulsion solution of the present invention, respectively. FIG. 3 is a graph showing the relationship between the amount of oil blended and the average particle size of the dispersoid. FIG. 4 is a graph showing the relationship between the amount of oil blended and the light transmittance of the emulsion.

1. Emulsion of the present invention The present invention relates to an emulsion that maintains a dispersoid stably over a long period of time despite its high concentration (hereinafter also referred to as the emulsion of the present invention). The emulsion of the present invention can maintain the stability of the emulsion over a long period of time when the average particle size of the dispersoid is in the range of 5 nm to 100 nm, and as a result, has a transparent or translucent appearance. As used herein, “transparent or translucent” refers to an indicator of the state in which the dispersoid is appropriately dispersed in the dispersion medium. Specifically, the light transmittance is 70 to water solvent ratio. % Or more. In the present invention, the light transmittance of the emulsion of the present invention is preferably 80% or more, more preferably 90% or more in terms of the ratio of water to water.

  In addition, the emulsion of the present invention is characterized in that the inclusion capacity of oil is remarkably higher than that of a micelle solution prepared from an amphiphilic molecule and water. More specifically, the emulsion of the present invention can be stably held without causing phase separation up to an oil content of about 2.0 times by weight with respect to the amount of amphiphilic molecules.

  That is, the emulsion of the present invention is a stable dispersion solution that includes an oil component that is a large amount of dispersoid exceeding the solubilization limit amount of the micelle solution prepared from an amphiphilic molecule and water. In addition, the solubilization limit amount with respect to the oil component of the amphiphilic molecule can be specified as follows according to the type of the amphiphilic molecule and the oil component. For example, when an oil component is mixed and dissolved in an amphiphilic molecular aqueous solution blended in an arbitrary amount, the amount at which the light transmittance of the aqueous solution is 70% or less in the ratio of water to solvent is determined as the solubilization limit amount. .

  Therefore, in the emulsion of the present invention, the blending amount of oil is 0.1 times or more, 0.2 times or more, 0.3 times or more, 0.4 times or more by weight with respect to the blending amount of the amphiphilic molecules 0.5 times or more, 0.6 times or more, 0.7 times or more, 0.8 times or more, 0.9 times or more, 1.0 times or more, 1.1 times or more, 1.2 times or more, 1 .3 times or more, 1.4 times or more, 1.5 times or more, 1.6 times or more, 1.7 times or more, 1.8 times or more, 1.9 times or more are included.

  On the other hand, the upper limit of the oil content that can be blended in the emulsion of the present invention is 2.0 times or less by weight ratio with respect to the blending amount of the amphiphilic molecule. As shown in the following examples, when the amount of oil component exceeds the above amount, the particle size of the dispersoid increases, or the oil component cannot be included in the dispersoid and leaks into the dispersion medium, This is because the stability of the emulsion is lowered.

  Furthermore, the emulsion of the present invention has a characteristic that the oil content in the dispersoid leaks and becomes cloudy when a high shearing force is applied, such as stirring treatment or ultrasonic treatment. Therefore, the emulsion of the present invention can be applied to external preparations for skin (for example, cosmetics), quasi-drugs or pharmaceutical preparations as external environment-responsive nanocapsules to which the above characteristics are applied.

  Of course, the emulsion of the present invention is not limited to the above application fields, and can also be applied to industrial products such as paints, inks, detergents, foodstuffs, and energy.

2. Emulsion constituents The emulsion of the present invention contains amphiphilic molecules, water and oil. In the emulsion of the present invention, the amphiphilic molecule and oil constitute a dispersoid, and water constitutes a dispersion medium.

  The amphiphilic molecule that can be used in the present invention is any ionic or nonionic compound having a hydrophilic group and a hydrophobic group, and any compound may be used in the present invention. Preferably, a surfactant is used as the amphiphilic molecule.

  The surfactant that can be used in the present invention is not particularly limited as long as it can form a discontinuous cubic liquid crystal by combining water and oil, and if necessary, a polyhydric alcohol, an auxiliary surfactant, and the like. Any of nonionic surfactants, cationic surfactants, anionic surfactants and amphoteric surfactants may be used. Preferably, a nonionic surfactant is used.

  The nonionic surfactant used in the present invention may be any of an ester type, an ether type, an ester / ether type, and an amino acid type nonionic surfactant. For example, but not limited to, polyoxyethylene hydrogenated castor oil, polyoxyethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene polyoxypropylene alkyl ether, polyglycerin fatty acid ester, sucrose fatty acid ester , Propylene glycol fatty acid ester, monoglycerin fatty acid ester, diglycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene fatty acid ester and the like.

  The polyoxyethylene hydrogenated castor oil used in the present invention can have any average degree of polymerization of ethylene oxide. Preferably, the lower limit of the average degree of polymerization of ethylene oxide is about 10 or more, and the upper limit of the average degree of polymerization of ethylene oxide is about 200 or less. Examples of preferred polyoxyethylene hydrogenated castor oil include polyoxyethylene hydrogenated castor oil 40, polyoxyethylene hydrogenated castor oil 60, and polyoxyethylene hydrogenated castor oil 80. This number represents the degree of polymerization of ethylene oxide. For example, polyoxyethylene hydrogenated castor oil 40 indicates that the average degree of polymerization of ethylene oxide is 40.

  The polyoxyethylene alkyl ether used in the present invention can have any average degree of polymerization of ethylene oxide. Preferably, the lower limit of the average degree of polymerization of ethylene oxide is about 10 or more, and the upper limit of the average degree of polymerization of ethylene oxide is about 20 or less. Examples of preferred polyoxyethylene alkyl ethers include polyoxyethylene cetyl ether, polyoxyethylene stearyl ether (also referred to as POE stearyl ether), polyoxyethylene octyl dodecyl ether (also referred to as POE octyl dodecyl ether) and polyoxyethylene isostearyl. And ether (also referred to as POE isostearyl ether).

  The polyoxyethylene sorbitan fatty acid ester used in the present invention may have any average degree of polymerization of ethylene oxide. The lower limit of the average degree of polymerization of ethylene oxide is about 10 or more, and the upper limit of the average degree of polymerization of ethylene oxide is about 20 or less. Examples of preferred polyoxyethylene sorbitan acid esters include polyoxyethylene sorbitan monooleate (also referred to as POE sorbitan monooleate), polyoxyethylene sorbitan monolaurate (also referred to as POE sorbitan monolaurate), polyoxyethylene sorbitan Examples include monostearate (also referred to as POE sorbitan monostearate), polyoxyethylene sorbitan monopalmitate (also referred to as POE sorbitan monopalmitate) and polyoxyethylene sorbitan trioleate (also referred to as POE sorbitan trioleate).

  The polyoxyethylene polyoxypropylene alkyl ether used in the present invention can have any average degree of polymerization of ethylene oxide. Preferably, the lower limit of the average degree of polymerization of the polyoxyethylene portion is about 10 or more, and the upper limit of the average degree of polymerization of the polyoxyethylene portion is about 20 or less. Preferably, the lower limit of the average degree of polymerization of the polyoxypropylene part is about 4 or more, and the upper limit of the average degree of polymerization of the polyoxypropylene part is about 8 or less. Examples of preferred polyoxyethylene polyoxypropylene alkyl ethers include polyoxyethylene polyoxypropylene cetyl ether, polyoxyethylene polyoxypropylene decyl tetradecyl ether and polyoxyethylene isostearyl ether.

  Examples of the polyglycerol fatty acid ester used in the present invention include decaglycerol monolaurate, decaglycerol monomyristate, decaglycerol monooleate and decaglycerol monostearate.

  Examples of sucrose fatty acid esters used in the present invention include sucrose stearate, sucrose oleate, sucrose palmitate, sucrose myristic ester, and sucrose laurate.

  The amino acid surfactant used in the present invention is not limited thereto, but is not limited thereto, for example, but, for example, lauroyl glutamate dioctyldecess-2, lauroylglutamate dioctyldecess -5, lauroyl glutamate distealess-2, lauroyl glutamate disteales-5, PCA isostearic acid PEG-30 hydrogenated castor oil, PCA isostearic acid PEG-40 hydrogenated castor oil, PCA isostearic acid PEG-60 hydrogenated castor oil, PCA isostearic It can be selected from the group consisting of acid glyceres-25.

By the way, the nonionic surfactant used in the present invention is not limited to such a chemical structure, but preferably has a HLB value of about 10 or more in terms of physical properties. When the HLB value of the nonionic surfactant is less than about 10, cubic liquid crystals may not be appropriately prepared. The term “HLB value” used in the present specification refers to a hydrophilic-hydrophobic balance, generally 20 × M _H / M (where M _H = molecular weight of the hydrophilic group part). Yes, M = molecular weight of the whole molecule). The HLB value is 0 when the amount of the hydrophilic group in the molecule is 0%, and 20 when the amount is 100%. The HLB value represents the size and strength of hydrophilic and hydrophobic groups that form a surfactant molecule in a surfactant, and a surfactant having a high hydrophobicity has a small HLB value and a high hydrophilicity. Has a large HLB value.

  One nonionic surfactant may be used alone, or a plurality of nonionic surfactants may be used in combination. In the present invention, preferable nonionic surfactants include, for example, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene hydrogenated castor oil, polyoxyethylene sorbitan monooleate, polyoxyethylene Examples include polyoxypropylene cetyl ether.

  On the other hand, the cationic surfactant that can be used in the present invention may be any cationic surfactant of amine salt type, alkyl quaternary ammonium salt type, or cyclic quaternary ammonium salt type. Specific examples include, but are not limited to, diethylaminoethylamide stearate, lauryltrimethylammonium chloride, lauryltrimethylammonium bromide, dialkyldimethylammonium chloride, and benzalkonium chloride.

  Anionic surfactants that can be used in the present invention include fatty acid salt type, alkyl ether carboxylate type, acyl lactate type, N-acyl sarcosine salt type, N-acyl glutamate type, N-acyl methyl type. Alanine salt type, N-acylmethyl taurine salt type, alkane sulfonate type, α-olefin sulfonate type, alkyl sulfosuccinate type, acyl isethionate type, alkyl sulfate salt type, alkyl ether sulfate salt type, Any of fatty acid alkanolamide sulfate salt type, monoacylglycerol sulfate ester salt type, and polyoxyethylene alkyl ether phosphate ester salt type may be used. Specifically, but not limited to, coconut oil fatty acid potassium, polyoxyethylene lauryl ether acetic acid, polyoxyethylene lauryl ether potassium acetate, sodium stearoyl lactate, lauroyl sarcosine triethanolamine, potassium myristoyl glutamate, coconut Oil fatty acid methylalanine, lauroylmethylalanine triethanolamine, sodium cocoylmethylaminoethyl sulfonate, sodium tetradecene sulfonate, disodium lauryl sulfosuccinate, sodium coconut oil fatty acid ethyl ester sulfonate, alkyl sulfate triethanolamine, alkyl ether sulfate Sodium, polyoxyethylene alkyl ether triethanolamine sulfate, hydrogenated coconut oil fatty acid sodium glyceryl sulfate It may be selected from polyoxyethylene alkyl ether phosphate triethanolamine.

  As the amphoteric surfactant that can be used in the present invention, any of amphoteric surfactants such as betaine type, sulfobetaine type, alkylbetaine type, imidazoline type, and lecithin may be used. Specific examples include, but are not limited to, lauryl betaine, cocamidopropyl betaine, cocamidopropyl hydroxysultain, egg yolk lecithin, soybean lecithin, and the like.

  The water used in the present invention is any water known to those skilled in the art. For example, although not limited to this, tap water, distilled water, ion exchange water, sterilizing water, etc. can be used.

  Oils that can be used in the present invention include vegetable oils such as wheat germ oil, corn oil, sunflower oil, and soybean oil, silicone oil, isopropylmyristate, glyceryl trioctanoate, diethylene glycol monopropylene pentaerythritol ether, and pentaerythrityl. Examples include, but are not limited to, ester oils such as tetraoctanoate, squalane, squalene, liquid paraffin, and polybutene. One oil may be used alone, or a plurality of oils may be used in combination.

3. Other Components The emulsion of the present invention can further contain a cosurfactant or a water-soluble additive such as a polyhydric alcohol, an inorganic salt, a water-soluble polymer, other water-soluble compounds, and the like.

  The auxiliary surfactant may be useful in that it can reduce the interface film curvature and facilitate the formation of a stable dispersoid. Examples of the cosurfactant that can be used in the present invention include, but are not limited to, cholesterol, phytosterol, and higher alcohol.

  The polyhydric alcohol may be useful in that the dispersoid can be stabilized. Examples of the polyhydric alcohol that can be used in the present invention include, but are not limited to, polyalkylene glycols such as polymethylene glycol and polyethylene glycol, glycerin, propylene glycol, 1,3-propanediol, 2- Butene-1,4-diol, pentane-1,5-diol, 2,2-dimethylpropane-1,3-diol, 3-methylpentane-1,5-diol, pentane-1,2-diol, 2, Examples include 2,4-trimethylpentane-1,3-diol, 2-methylpropane-1,3-diol, hexylene glycol, 1,3-butylene glycol, dipropylene glycol, diethylene glycol, and triethylene glycol. A polyhydric alcohol may be used individually by 1 type, and may be used in combination of multiple types.

  The inorganic salt may be useful in that the dispersoid can be stabilized by changing the hydration state of the hydrophilic group of the amphiphilic molecule. Examples of inorganic salts that can be used in the present invention include, but are not limited to, sodium chloride, sodium bromide, potassium chloride, sodium acetate, potassium bromide, calcium chloride, magnesium chloride, zinc chloride, and chloride. Examples thereof include iron and zinc acetate. One inorganic salt may be used alone, or a plurality of inorganic salts may be used in combination.

  The water-soluble polymer may be useful in that the dispersoid can be stabilized by the excluded volume effect or the electric repulsive effect. Water-soluble polymers that can be used in the present invention include, but are not limited to, polyvinyl alcohol, carboxyvinyl polymer, hyaluronic acid, collagen, polylysine, chitosan, polypeptide, oxyethylene-oxypropylene copolymer Examples thereof include a copolymer, an acrylic acid / alkyl methacrylate copolymer, and an alkyl acrylate copolymer. A water-soluble polymer may be used individually by 1 type, and may be used in combination of multiple types.

  Examples of other water-soluble compounds that can be used in the emulsion of the present invention include, but are not limited to, urea, lactic acid, glycolic acid, water-soluble amino acids, and sugars.

  The emulsion of the present invention can contain, in addition to the above components, an aqueous or oily additional component that is usually used in cosmetics and pharmaceuticals or as a raw material thereof. Examples of such additional ingredients include humectants, preservatives, antioxidants, UV absorbers, cosmetic ingredients, vitamins, fragrances, fragrances, thickeners, colored pigments, glitter pigments, organic powders , Metal oxides, tar pigments and the like.

Hereinafter, exemplary ranges of the blending amount of each component constituting the emulsion of the present invention will be described.
-The compounding quantity of an amphiphilic molecule | numerator is 0.001-25 weight% per total weight of the emulsion of this invention, Preferably it is 0.01-20 weight%.
-The compounding quantity of water is 10-99.9 weight% with respect to the total weight of the emulsion of this invention, Preferably it is 30-99.9 weight%.
-The compounding quantity of an oil component is 0.0001-50 weight% per total weight of the emulsion of this invention, Preferably it is 0.001-40 weight%, More preferably, it is 0.001-35 weight%.
-The compounding quantity of an auxiliary surfactant is 0 to 20 weight% with respect to the total weight of the emulsion of this invention, Preferably it is 0.001 to 10 weight%.
-The compounding quantity of a polyhydric alcohol is 0 to 80 weight% with respect to the total weight of the emulsion of this invention, Preferably it is 0.1 to 70 weight%.
-The compounding quantity of an inorganic salt is 0 to 15 weight% with respect to the total weight of the emulsion of this invention, Preferably it is 0.001 to 10 weight%.
-The compounding quantity of a water-soluble polymer is 0 to 10 weight% per total weight of the emulsion of this invention, Preferably it is 0.001 to 5 weight%.

4). Applications The emulsion of the present invention is prepared by further blending an active ingredient of cosmetics or pharmaceuticals into the dispersoid, so that external externally responsive nanocapsules can be used as external preparations for skin (for example, cosmetics, quasi-drugs for external use, pharmaceuticals), pharmaceuticals Can be provided.

  The active ingredient that can be used in the present invention is not particularly limited as long as it is an oil-soluble compound. For example, retinoic acid, lipoic acid, prednisolone, glycyrrhetinic acid, indomethacin, naproxen, docosahexaenoic acid, eicosapentaenoic acid, tamibarotene Chlorogenic acid, retinol, finasteride, azathioprine, chlorpromazine, phenytoin, diazepam, donepezil hydrochloride, aspirin, levodopa, prostaglandin derivative, beclomethasone propionate, theophylline, lidocaine hydrochloride, nicotinic acid, nateglinide, colchicine, vitamin D, flavonoid , Azathioprine, methotrexate, fluorouracil, mercaptopurine, paclitaxel, doxorubicin hydrochloride, imatinib mesylate, shirori Scan, oil-soluble peptides, testosterone, estrogen, tocopherols, carotenoids, can be used linoleic acid, pentadecanoic acid, crude drug extracts, Ascorbyl Tetraisopalmitate, ellagic acid, retinol palmitate, ceramides, and the like.

  Of course, the emulsion of the present invention is not limited to the above application fields, and can also be applied to industrial products such as paints, inks, detergents, foodstuffs, and energy.

5. Method for Preparing Emulsion Hereinafter, a method for preparing the emulsion of the present invention will be exemplified.

  The emulsion of the present invention is a first step of preparing a discontinuous cubic liquid crystal, and preparing a transparent or translucent aqueous solution by diluting the liquid crystal with water or an aqueous solution containing a water-soluble additive. And the second step. Discontinuous cubic liquid crystal is a liquid crystal structure unit where one of the hydrophobic and hydrophilic regions has a continuous structure, while the other has a discontinuous structure. Say what you are.

  The first step is a step of preparing a discontinuous cubic liquid crystal by mixing amphiphilic molecules, water and oil. At that time, the blending amount is adjusted so that the amount of the oil component is 2 times or less by weight with respect to the amphiphilic molecule. This is because when the blending amount of oil exceeds the above ratio, the emulsion of the present invention cannot be formed as shown in the following examples (see, for example, FIGS. 3 and 4).

  Optional co-surfactants and water-soluble additives (polyhydric alcohols, inorganic salts, water-soluble polymers, other water-soluble compounds) are added to the amphiphilic molecules in the first step of preparing the discontinuous cubic liquid crystals. What is necessary is just to mix | blend with water and an oil component. Moreover, what is necessary is just to mix | blend at this time, also when mix | blending an oil-soluble compound as an active ingredient of cosmetics or a pharmaceutical.

  In the first step, the discontinuous cubic liquid crystal is obtained by adding and mixing the above-mentioned amphiphilic molecules, water and oil, and other optional components (co-surfactant and water-soluble additive). Can be prepared and does not require any special method. In addition, when an amphiphilic molecule or an auxiliary surfactant is added, a treatment such as heating may be appropriately performed.

  The amount of each component constituting the discontinuous cubic liquid crystal is particularly as long as the discontinuous cubic liquid crystal can be formed, except that the oil content is not more than twice the weight ratio to the amphiphilic molecule. Not limited. The amount of each component can be appropriately selected according to the type of amphiphilic molecule, oil, etc. used. For example, it is possible to find a blending ratio for forming a discontinuous cubic liquid crystal by creating a phase equilibrium diagram having amphiphilic molecules and oil components to be used and water as items.

Hereinafter, exemplary amounts of each component used for preparing a discontinuous cubic liquid crystal will be described.
-The compounding quantity of an amphiphilic molecule is 10 to 60 weight% with respect to the total weight of a discontinuous cubic liquid crystal, Preferably it is 15 to 45 weight%.
-The compounding quantity of water is 5-90 weight% per total weight of a discontinuous cubic liquid crystal, Preferably it is 10-80 weight%.
-The compounding quantity of oil is 1-60 weight% per total weight of a discontinuous cubic liquid crystal, Preferably it is 5-45 weight%.
-The compounding quantity of an auxiliary surfactant is 0 to 20 weight% with respect to the total weight of a discontinuous cubic liquid crystal, Preferably it is 0.1 to 10 weight%.
-The compounding quantity of a polyhydric alcohol is 0 to 75 weight% with respect to the total weight of a discontinuous cubic liquid crystal, Preferably it is 5 to 50 weight%.
-The compounding quantity of an inorganic salt is 0 to 15 weight% with respect to the total weight of a discontinuous cubic liquid crystal, Preferably it is 0.1 to 10 weight%.
-The compounding quantity of a water-soluble polymer is 0 to 10 weight% with respect to the total weight of a discontinuous cubic liquid crystal, Preferably it is 0.1 to 5 weight%.

  In the present invention, it is confirmed, for example, by polarizing microscope observation, small-angle X-ray scattering measurement, viscosity measurement, and dye staining method that the mixture prepared as described above forms a discontinuous cubic liquid crystal. Can do.

  The subsequent second step is a step of preparing a transparent or translucent aqueous solution (ie, emulsion) by diluting the discontinuous cubic liquid crystal prepared in the first step with water or an aqueous solution containing a water-soluble additive. It is.

  The amount of water to be added or an aqueous solution containing a water-soluble additive is not particularly limited as long as it is an amount that dilutes a discontinuous cubic liquid crystal to produce a transparent or translucent aqueous solution. What is necessary is just to select it by the amount more than the same size as cubic liquid crystal. Alternatively, the amount of water or an aqueous solution containing a water-soluble additive is, for example, that the amount of oil-soluble compound blended as an active ingredient in a discontinuous cubic liquid crystal is appropriate depending on products such as cosmetics and pharmaceuticals. It may be selected to be diluted to a concentration.

  When the discontinuous cubic liquid crystal is diluted with an aqueous solution containing a water-soluble additive, the amount of the water-soluble additive in the aqueous solution is the same as the discontinuous cubic liquid crystal prepared in the first step. It varies depending on the presence or amount of water-soluble additives in the medium. That is, what is necessary is just to set so that it may become in the range of the total amount of the water-soluble additive mix | blended with the emulsion of this invention illustrated above.

  In the second step, it is preferable that the dilution of the discontinuous cubic liquid crystal does not give an excessive shearing force. This is because when an excessive shear force is applied, the dispersion state of the emulsion collapses as described later, and an appropriate emulsion cannot be formed. Specifically, it is preferable to prepare a transparent emulsion using a shearing force of less than 3000 rpm at a stirring speed.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to a present Example.

(1) Reagents The reagents used in this test are as follows.
Polyoxyethylene octyldodecyl ether: Emulgen 2020G-HA (HLB: 13.0) manufactured by Kao Chemical Co., Ltd.
Glycerin: Concentrated glycerin squalane manufactured by Kao Chemical Co., Ltd .: Purified olive squalane, ethyl hexanoate cetyl manufactured by Nikko Chemicals Co., Ltd .: CIO manufactured by Nikko Chemicals

(2) Preparation of Emulsion Polyoxyethylene octyldodecyl ether (30 g), squalane (15 g), glycerin (38 g) and purified water (17 g) were weighed, and then the solution heated and mixed at 80 ° C. was cooled to room temperature. The liquid crystal structure of the composition was specified by using a combination of visual observation, polarization microscopy observation, small-angle X-ray scattering method, and dye staining method.

  Discontinuous cubic liquid crystal prepared in accordance with the above and purified water are mixed at a weight ratio of 5:95 (= discontinuous cubic liquid crystal: purified water) and dissolved with a weak stirring force using a stirrer bar. -Dispersed to obtain a transparent aqueous solution (Preparation Example 1).

  An external view of the emulsion of Preparation Example 1 and a simple mixture having the same composition as Preparation Example 1 is shown in FIG. As is clear from FIG. 1, the emulsion prepared by the method of the present invention (right figure) has high transparency.

  Therefore, it was shown that the emulsion of Preparation Example 1 has a very small average particle size of the dispersoid.

(3) Stability verification of emulsion The stability of the emulsion of Preparation Example 1 was evaluated using a high shear homomixer (Primics Co., Ltd., Robomix MII-2.5). As a stability index, a light transmittance measured with a spectrophotometer (manufactured by Shimadzu Corporation, UVmini-1240, wavelength = 550 nm) was used. FIG. 2 shows the change over time in the light transmittance of the emulsion at each shear force (stirring speed). The light transmittance is calculated with the light transmittance of water as 100%.

  As can be seen from FIG. 2, it was found that the light transmittance of the emulsion decreased with time by applying a shearing force of 4000 rpm or more.

Further, using an ultrasonic generator (manufactured by Sharp Corporation, 35 kHz), the emulsion of Preparation Example 1 was irradiated with ultrasonic waves, and the stability of the emulsion was evaluated. Table 1 shows the relationship between the irradiation energy amount and the light transmittance.

  As is apparent from Table 1, it was found that the light transmittance of the emulsion of Preparation Example 1 decreased with increasing irradiation energy.

  According to the said result, it turned out that the dispersoid in the emulsion of the preparation example 1 collapse | disintegrates by applying a shearing force, and leaks an internal oil component. Therefore, it was suggested that the dispersoid of the emulsion may be micelle-like particles that include oil.

(4) Oil content inclusion ability of emulsion When preparing discontinuous cubic liquid crystals with different oil content and diluting with aqueous glycerin solution (glycerin weight fraction = 0.69), emulsion particle size and transparency Evaluated. Specifically, a discontinuous cubic liquid crystal was prepared with the components and composition (weight fraction) shown in Table 2 below, and an emulsion of discontinuous cubic liquid crystal: glycerin aqueous solution = 5: 95 was prepared by weight ratio. did.

  A plot of the particle size against the weight fraction (Xo) of cetyl ethylhexanoate is shown in FIG. As can be seen from FIG. 3, the particle size becomes extremely large when Xo = 0.5 or more.

  Moreover, what plotted the light transmittance with respect to the weight fraction (Xo) of cetyl ethylhexanoate is shown in FIG. As can be seen from FIG. 4, the light transmittance sharply decreases when Xo = 0.5 or more.

  From these results, it was found that the dispersoid in the emulsion can stably include the oil up to about 2 times the surfactant.

(5) Verification of structural characteristics of emulsion Discontinuous of Preparation Example 1 using dynamic light scattering (DLS, manufactured by Otsuka Electronics Co., Ltd., ELS-710TY), transmission electron microscope (TEM, manufactured by JEOL Ltd.) -Cubic liquid crystal was prepared and the structure of the emulsion when diluted with a glycerin aqueous solution (glycerin weight fraction = 0.69) was evaluated. Table 3 shows the average particle diameter with respect to each weight% of the discontinuous cubic liquid crystal.

  As can be seen from Table 3, it was a spherical particle of 15 to 40 nm irrespective of the concentration of the discontinuous cubic liquid crystal.

  ADVANTAGE OF THE INVENTION According to this invention, the nanoemulsion which can be manufactured simply and cheaply, has a high oil concentration, and was excellent in stability is provided.

  The emulsion of the present invention has a long-term emulsification stability characteristic and also has a characteristic that the contained oil component leaks when a high shear force is applied. Therefore, it is expected that the emulsion according to the present invention can be applied to cosmetics and pharmaceutical preparations as external environment-responsive nanocapsules to which the above characteristics are applied.

  The emulsion of the present invention can also be applied to industrial products such as paints, inks, detergents, foodstuffs, and energy.

Claims (7)

A method for preparing an emulsion comprising:
A first step of preparing a Discontinuous Cubic liquid crystal containing amphiphilic molecules, water and oil;
A second step of preparing a transparent or translucent aqueous solution by adding and diluting the liquid crystal with water or an aqueous solution containing a water-soluble additive, and
The amount of oil component are two-fold der less by weight relative to the amphiphilic molecule,
The method according to claim 1, wherein the discontinuous cubic liquid crystal has an oil-in-water structure .   The method according to claim 1, wherein the oil content is 0.5 to 2 times by weight with respect to the amphiphilic molecule.   The method of claim 1, wherein the second step is performed at a stirring speed under a shear force of less than 3000 rpm.   The method of claim 1, wherein the amphiphilic molecule is a nonionic surfactant.   The method according to claim 4, wherein the nonionic surfactant is polyoxyethylene dodecyl ether.   The method of claim 1, wherein the water-soluble additive is a polyhydric alcohol. The method according to claim 6, wherein the polyhydric alcohol is glycerin.

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