Method for producing cerac particles

Abstract

To provide a method for producing shellac fine particles comprising natural resin suitable for skin care uses such as makeup, a facial cleanser, and body soap.SOLUTION: According to a method for producing shellac fine particles, a shellac solution prepared by adding shellac to a good solvent is made to coexist with a dispersion stabilizer and a surfactant; a solution containing phosphate ions is added to a solution containing shellac fine particles prepared by addition of a poor solvent and calcium ions, under basic conditions; and after the addition, the basic conditions are changed into neutral conditions.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing particulate shellac.

Background Art

[0002] Organic fine particles synthesized from raw materials such as methyl methacrylate, styrene, nylon, and urethane and having particle diameters on the nano or micro order are used in skin care applications as additives for cosmetics, scrubbing agents such as facial cleansers and body soaps, taking advantage of their stretchability and light diffusibility.

[0003] In skin care applications such as cosmetics, facial cleansers, and body soaps, it has been pointed out that when they are washed after use and discharged into the environment as wastewater, they affect the ecosystem as so-called microbeads. In addition, since organic fine particles are made from petroleum-derived components, concerns about the environmental load have also been pointed out.

[0004] On the other hand, although natural resins can be obtained without imposing a load on the environment, many of them are in the form of gums or chips. It has been difficult to make them into fine particles and use them as a substitute for organic fine particles.

Prior Art Documents

Patent Documents

[0005] Patent Document 1 discloses a decorative edible metal foil obtained by processing shellac, which is a natural resin, into a film. However, it is not a technique for processing into fine particles and cannot replace organic fine particles.

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a method for producing shellac fine particles suitable for skin care applications such as cosmetics, facial cleansers, and body soaps.

Means for Solving the Problems

[0007] A method for producing shellac fine particles, comprising a step of adding a solution containing phosphate ions to a solution containing shellac fine particles and calcium ions under basic conditions.

Effects of the Invention

[0008] By the production method of the present invention, shellac fine particles suitable for skin care applications such as cosmetics, facial cleansers, and body soaps can be easily obtained. In particular, it is excellent in that it does not require special equipment, has a small amount of by-products, and is easy to handle.

Modes for Carrying Out the Invention

[0009] The production method of the present invention includes a step of adding a solution containing phosphate ions to a solution containing shellac fine particles and calcium ions under basic conditions. By this step, heat resistance can be imparted to the shellac fine particles, and it becomes difficult to fuse even at high temperatures.

[0010] Shellac can be obtained by purifying the resinous substance (seed lac) secreted by the lac bug by a heat melting method, an alkali extraction method, a solvent extraction method, or the like. Shellac fine particles can be produced from shellac obtained by any method, but when producing shellac fine particles suitable for skin care applications such as cosmetics, facial cleansers, and body soaps, it is particularly preferable to use shellac purified to conform to the raw material standards for quasi-drugs.

[0011] Examples of the method for producing shellac fine particles include a method in which a dispersion stabilizer or a surfactant coexists in a solution in which shellac is dissolved in a good solvent, and spherical shellac is precipitated by reducing the solubility of shellac by adding a poor solvent.

[0012] As a good solvent for shellac, known liquid alcohols can be used, such as monohydric to trihydric alcohols like methyl alcohol, ethyl alcohol, n-propanol, n-butanol, ethylene glycol, and glycerin, and branched alcohols like isopropyl alcohol, isobutyl alcohol, tert-butyl alcohol, and isoamyl alcohol. Examples include these substances alone or mixtures of two or more in any proportion. Among the exemplified good solvents, methyl alcohol, ethyl alcohol, n-propanol, n-butanol, isopropyl alcohol, isobutyl alcohol, and tert-butyl alcohol, which can easily dissolve shellac and have low boiling points and are thus easy to distill off, are preferred, and among them, methyl alcohol and ethyl alcohol are more preferred. As a poor solvent for shellac, it is a liquid that is mixed with the above good solvent, and water is particularly preferred. Water as a poor solvent may contain water-soluble inorganic and organic components such as electrolytes without problems, but it is more preferred to use distilled water or ion-exchanged water.

[0013] Examples of the dispersant used in the production of the shellac fine particles include water-soluble polymers such as gelatin, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyethylene glycol, polyoxyethylene-polyoxypropylene block copolymer, polyacrylamide, polyacrylic acid, polyacrylate, sodium alginate, polyvinyl alcohol, and polyvinylpyrrolidone, which can be used alone or in combination of two or more. Inorganic substances such as tricalcium phosphate, titanium oxide, calcium carbonate, and colloidal silica may also be used in combination. The blending amount of the dispersant may be about 0.05 to 30 parts by weight with respect to 100 parts by weight of shellac.

[0014] Examples of the surfactant used in the production of the shellac fine particles include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, and polymeric surfactants, etc., which can be used alone or in combination of two or more. The blending amount of the surfactant may be about 0 to 10 parts by weight with respect to 100 parts by weight of shellac.

[0015] As the compound serving as a calcium ion source, known water-soluble calcium compounds can be used, and examples thereof include calcium nitrate, calcium nitrate tetrahydrate, calcium chloride, calcium chloride monohydrate to hexahydrate, calcium lactate, calcium chlorate dihydrate, calcium perchlorate, calcium bromide, calcium acetate, calcium glutamate, etc., and they can be used alone or in combination of two or more. For 1 g of the cerac, calcium ions are made to act in an amount of 1.36×10 -3 mol or more, preferably 2.72×10 -3 mol or more, and more preferably 4.1×10 -3 mol or more. By making it act in an amount of 4.1×10 -3 mol or more, sufficient hydroxyapatite coating becomes easy.

[0016] As the compound serving as a phosphate ion source, known water-soluble phosphate compounds can be used, and examples thereof include diammonium hydrogen phosphate, ammonium dihydrogen phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate monohydrate, sodium dihydrogen phosphate dihydrate, potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, etc., and they can be used alone or in combination of two or more. For 1 g of the cerac, phosphate ions are made to act in an amount of 4.52×10 -3 mol or more, preferably 9.04×10 -3 mol or more, and more preferably 1.36 mol×10 -3 mol or more. By making it act in an amount of 1.36 mol×10 -3 mol or more, sufficient hydroxyapatite coating becomes easy. If the concentrations of calcium ions and phosphate ions are increased, high heat resistance can be imparted to the cerac fine particles, and thus the concentrations are appropriately adjusted according to the required heat resistance.

[0017] The range of the basic condition is pH = 7.8 or higher, preferably pH = 8 or higher, and more preferably pH = 9 or higher. By setting the pH to 9 or higher, the precipitation rate of hydroxyapatite becomes optimal, and the hydroxyapatite coating layer is likely to be formed. Examples of additives for making the solution basic include ammonia, sodium hydroxide, potassium hydroxide, etc. Among these, ammonia is preferred because it is easily removed during drying. The addition amount is not particularly limited as long as the above basic conditions are satisfied.

[0018] The treatment for hydroxyapatite conversion is achieved by adding an aqueous solution containing phosphate ions to a solution containing silac microparticles and calcium ions under the above basic conditions. When performing the hydroxyapatite conversion treatment, the temperature may be constant, or may be changed during the process or at each stage. For example, a temperature range of 0 to 95°C can be exemplified. The method of adding phosphate ions is not particularly limited, and known methods such as a method of charging all the amount at once at the beginning, a method of charging a part at the beginning and continuously feeding and adding the remaining amount, and a method of adding intermittently can be adopted. The time for adding the solution containing phosphate ions is also not particularly limited and can be appropriately set. For example, a time range of 0.5 to 120 minutes from the start to the end can be exemplified. The reaction time after adding phosphate ions is also not particularly limited and can be appropriately set according to the progress of the reaction. For example, a time range of 5 to 180 minutes can be exemplified.

[0019] The range of the neutral condition is pH = 5 to 7.8, preferably pH = 6 to 7.5 or higher, and more preferably pH = 6.8 to 7.5. By setting the pH to 6.8 to 7.5, the alkali swelling of the silac microparticles is sufficiently eliminated, the filterability becomes good, and the microparticles after drying are likely to exhibit heat resistance. Examples of additives for making the solution neutral include inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, and organic acids such as formic acid, acetic acid, oxalic acid, citric acid, and p-toluenesulfonic acid. The addition amount is not particularly limited as long as the above neutral conditions are satisfied. Regarding the reaction temperature and time under neutral conditions, there is no particular limitation as long as the above-mentioned neutral conditions are satisfied. For example, at room temperature (25°C, 65% RH), the time can be 0.5 to 120 minutes.

[0020] In the extraction step, the solvent and water are removed to obtain shellac fine particles. It is necessary to remove the solvent first, but a part of the water may be removed at this time. If the solvent has a lower boiling point than water, for example, by reducing the pressure, it can be removed prior to water. By such an operation, only the solvent is removed from the shellac fine particle dispersion to obtain a shellac fine particle aqueous dispersion.

[0021] By removing the water from the shellac fine particle aqueous dispersion, shellac fine particles are obtained. The removal of water is carried out by known methods such as filtration, centrifugal dehydration, and vacuum drying. Since the thus-obtained shellac fine particles may contain secondary aggregates or coarse particles, if necessary, pulverization using a hammer mill or the like and purification by sieving, air classification, etc. may be performed.

[0022] The shellac fine particles thus obtained are substantially spherical with a particle diameter of about 3 to 20 μm, and thus can be used in various applications where organic fine particles are used. In particular, in skin care applications such as cosmetics, facial cleansers, and body soaps, they can be used in the same manner as conventional organic fine particles, and even if they are washed after use and released into the environment as wastewater, they are biodegradable and thus have a small environmental load.

[0023] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but these are merely specific examples and are not particularly limited thereto. When there is no notation, the experiments were carried out under the conditions of room temperature of 25°C and relative humidity of 65%.

Examples

[0024] Example 1 140 g of methanol was charged into a separable flask equipped with a stirrer, and the temperature was raised to 40 °C while stirring. 50 g of shellac (trade name: manufactured by Koyo Chemical Co., Ltd., dry transparent shellac) and 10 g of polyvinylpyrrolidone (trade name: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Pittscole K-90) were charged and dissolved, and the shellac solution was prepared by cooling to room temperature. While stirring the shellac solution, 120 g of ion-exchanged water as a poor solvent was added to precipitate fine particles. This dispersion was diluted with 300 g of ion-exchanged water, and 4 g of calcium chloride dihydrate was added. Then, 10 g of 28% aqueous ammonia was added to the shellac fine particle dispersion to adjust the pH of the dispersion to 9.0. To this dispersion, 42 g of 5 wt% ammonium hydrogen phosphate was added dropwise over 30 minutes and reacted at room temperature for 1 hour. Then, 8.5 g of acetic acid was added and stirred for 10 minutes to obtain a dispersion of hydroxyapatite-coated shellac fine particles with a pH of 7.2. After distilling off the methanol, the dispersion was filtered and washed with pure water. The obtained filtrate was dried to recover the fine particles. When the volume average particle diameter of the obtained fine particles was measured with an electrical resistance method particle size distribution measuring device (Beckman Coulter, Inc., Multisizer 3), it was 4.1 μm.

[0025] Examples 2 to 4 In the production method of Example 1, each fine particle of Examples 2 to 4 was obtained in the same manner as in Example 1 except that the addition amounts of the respective components were changed as shown in Table 1.

[0026] Comparative Example 1 Shellac fine particles were precipitated in the same manner as in Example 1. Then, methanol was distilled off, the dispersion was filtered and washed with pure water. The obtained filtrate was dried to recover the fine particles. When the volume average particle diameter of the fine particles was measured in the same manner, it was 3.6 μm.

[0027] Comparative Example 2 Cerac micro-particles were deposited in the same manner as in Example 1. Further, the adjusted dispersion was diluted with 300 g of ion-exchanged water, and 4 g of calcium chloride dihydrate was added. To this dispersion, 42 g of 5 wt% ammonium dihydrogen phosphate was added dropwise over 30 minutes, and then reacted at room temperature for 1 hour to obtain a dispersion of hydroxyapatite-coated Cerac micro-particles. Similarly, methanol was distilled off, and the dispersion was filtered and washed with pure water. The obtained filtrate was dried to recover the particles. When the volume average particle diameter of the micro-particles was measured in the same manner, it was 3.8 μm.

[0028]

Table 1

[0029] 5 g of each Cerac micro-particle of the example and the comparative example was weighed into an aluminum petri dish, placed in an oven set at 50 °C, 80 °C, and 100 °C respectively, heated for 5 hours, and then observed with a scanning electron microscope (JEOL Ltd., JSM-6510LV). The heat resistance was evaluated as ○ when the spherical state could be maintained, △ when partial fusion occurred, and × when the state was fusion or melting.

[0030]

Table 2

[0031] The tactile sensation of each Cerac micro-particle of the example and the comparative example was evaluated. PMMA micro-particles (Aica Industries Co., Ltd., Guns Pearl GMX-0610) industrially produced and used were used as a reference sample. 0.1 g of each powder was taken in the hand, spread on the back of the hand, and rubbed with the finger, and the sensory evaluation was compared for "good slipperiness" and "whether a squeaking feeling is felt". Using 10 panelists, it was evaluated as 〇 when 7 or more people evaluated it as good, △ when 4 to 6 people evaluated it as good, and × when 3 or fewer people evaluated it as good.

[0032]

Table 3

[0033] Each shellac microparticle of the examples had a touch feeling equivalent to that of organic microparticles and had practical heat resistance. On the other hand, the microparticles of Comparative Example 1 in which the step of adding a solution containing phosphate ions to a solution containing shellac microparticles and calcium ions was not performed itself, and the microparticles of Comparative Example 2 in which the step was performed but not under basic conditions had inferior heat resistance and touch feeling.

Claims

1. A method for producing hydroxyapatite-coated shellac microparticles, comprising a step of adding a solution containing phosphate ions (except when the phosphate ions are phospholipids) to a solution containing shellac microparticles and calcium ions under basic conditions.

2. The method for producing hydroxyapatite-coated shellac microparticles according to Claim 1, wherein after the step, the condition is made neutral.

3. The method for producing hydroxyapatite-coated shellac microparticles according to Claim 1 or 2, wherein the shellac microparticles are produced by a step of adding a poor solvent after preparing a shellac solution by adding shellac to a good solvent.

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