Multifunctional microcapsules, methods of making and using the same

Abstract

The application discloses a multifunctional microcapsule which is prepared by mixing polylactic acid and chitosan derivatives to form a microcapsule shell layer and using an ultraviolet absorber as a core material. The method is simple, the multifunctional microcapsule has good protection on the core material, can play a role for a long time, and avoids a large amount of burst release of the core material in a short time. The raw materials are safe and environmentally friendly. The prepared microcapsule can absorb ultraviolet light and oil when released. The multifunctional microcapsule can be applied in the fields of cosmetics, paints and special materials, and the influence of ultraviolet light is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microcapsule materials, in particular to a multifunctional microcapsule, a preparation method and application thereof, which is suitable for application in medicines, cosmetics and functional materials. BACKGROUND

[0002] Microcapsule refers to a continuous thin film (wall or outer phase) of various natural or synthetic high molecular compounds completely covering a target object (core or inner phase) without damaging the original chemical properties of the target object, and then gradually presenting the function of the target object again through certain external stimulation or slow release, or relying on the shielding effect of the capsule wall to protect the core material. The diameter of microcapsule is generally 1-500 μm, and the thickness of the wall is 0.5-150 μm. The embedded substance is called core material, including fragrances, acidifiers, sweeteners, pigments, lipids, vitamins, minerals, enzymes, microorganisms, gases and other various additives, and the substance that realizes the microcapsule of the embedded core material is called wall material.

[0003] Polylactic acid, also known as polylactide, is a polyester polymer obtained by polymerization of lactic acid. Polylactic acid has good solvent resistance, excellent mechanical properties and physical properties. It can be processed in various ways, including extrusion, blow molding, stretching, spinning, etc. The material prepared from polylactic acid not only has good biodegradability, but also has good biocompatibility, transparency, heat resistance, hand feeling and glossiness. Due to the above advantages, polylactic acid is widely used in clothing, packaging materials, fibers, non-wovens, construction, chemical industry and medical health fields, and is used as a wall material for microcapsules here.

[0004] Natural polysaccharides are attracting attention due to their high efficiency, environmental protection, biodegradability and low cost. For example, chitosan in various forms of powder, sheet, bead and film shows excellent adsorption capacity due to the presence of amino and hydroxyl functional groups. Chitosan is a good polysaccharide material, which is widely concerned due to its characteristics of oil absorption and versatility of modification, and has the characteristics of high material utilization rate, ecological friendliness and low risk of secondary pollution.

[0005] The common microcapsule has the following problems in the application of releasing core material, protecting active substances and other fields: (1) the microcapsule wall material has certain toxicity to the environment, most of the wall materials are not green and non-toxic materials, and may have side effects on the environment after degradation; (2) the protection of the core material is limited due to the insufficient mechanical properties of the wall material microcapsule; (3) the absorbed substances are released quickly, usually in a short time, the absorbed substances are released completely, and the long-term release function cannot be achieved; (4) the function of the microcapsule is single, and it cannot be used in various complex environments. SUMMARY

[0006] The primary objective of this invention is to address the problems existing in the prior art described above by providing a multifunctional microcapsule encapsulating an ultraviolet absorber.

[0007] A second objective of this invention is to provide a method for preparing the multifunctional microcapsules.

[0008] A third objective of this invention is to provide applications of the aforementioned multifunctional microcapsules.

[0009] To achieve the above-mentioned objectives, the technical solution adopted by this invention is: a multifunctional microcapsule, comprising the following weight proportions:

[0010]

[0011] The first solvent is used to dissolve polylactic acid and may be one or more of dichloromethane, n-butyl acetate, xylene, and chloroform.

[0012] The second solvent is used to dissolve chitosan and can be one or more of hydrochloric acid, acetic acid, and peracetic acid.

[0013] The third solvent, used to dissolve polyvinyl alcohol, can be deionized water.

[0014] The core material is at least one ultraviolet absorber, which may be one or more of the following: aminobenzoic acid, benzophenone, phenyl salicylate, ethylhexyl salicylate, humosalilate, 4-hydroxybenzophenone, p-methoxycinnamate isoamyl ester, benzophenone-3, 4-methylbenzyl camphor, PABA ethylhexyl ester, 2-cyano-3,3-diphenylacrylate-2-ethylhexyl ester, and butyl methoxydibenzoylmethane.

[0015] The emulsifier is one or more of lecithin, lanolin, gum arabic, N-dodecyl dimethylamine and other amine derivatives, quaternary ammonium salts, fatty acid soaps, alkyl sulfates (sodium dodecyl sulfate), alkylbenzene sulfonates (sodium dodecylbenzene sulfonate), or phosphates.

[0016] The polylactic acid is preferably polylactic acid of type 4060D with a molecular weight of approximately 320,000.

[0017] The polyvinyl alcohol is preferably polyvinyl alcohol with the model number PVA-1788.

[0018] The chitosan derivative can be prepared by the following steps: 1g of chitosan is mixed with 100ml of 5wt% acetic acid solution, and after the chitosan is fully dissolved, 100ml of anhydrous ethanol is added for dilution; 0.2-1.0g of octenyl succinic anhydride (OSA) is dissolved in 10-15ml of anhydrous ethanol until the solution is clear; finally, the OSA solution is slowly added dropwise to the chitosan solution, and the mixture is stirred at 200r / min in a 40° water bath for 4h. After the reaction, the pH of the solution is adjusted to 7-8 using a 5%wt NaOH solution. The precipitate is separated by centrifugation and dried to obtain the chitosan derivative with pH response function.

[0019] The preparation method of the multifunctional microcapsules includes the following steps: dissolving polylactic acid and a core material in a first solvent to form a polylactic acid / core material solution; adding a chitosan derivative to a second solution to form a chitosan derivative solution; adding polyvinyl alcohol to a third solution to form a polyvinyl alcohol solution; subsequently adding the chitosan derivative solution and a polyvinyl alcohol solution in an equal volume (1:1 mass ratio) to the chitosan derivative solution to the polylactic acid / core material solution, and ultrasonically treating with an ultrasonic power of 200-250W for 15-30 minutes to obtain a primary emulsion; Then, add the remaining polyvinyl alcohol solution and emulsifier to the primary emulsion and emulsify at 1500-2000 r / min for 30-45 min. After emulsification, stir at 200-400 r / min for 3 h in a 45-60° water bath to evaporate the first solvent and prepare multifunctional microcapsules. After completion, wash three times with deionized water in a centrifuge at 4000-6000 r / min. Finally, freeze-dry in a freeze dryer at -40-50°C for 48-72 h to obtain multifunctional microcapsules.

[0020] The multifunctional microcapsules are used as functional additives in pharmaceuticals, cosmetics, and functional materials.

[0021] The multifunctional microcapsules can be used as additives for functional fine organic chemicals such as cosmetics, and the amount added is 0.1-20% of the total mass.

[0022] Preferably, the amount added during use is 0.15-3% of the total mass.

[0023] The multifunctional microcapsules can be used in the preparation of adhesives and coatings, and the amount added is 1-30% of the total mass.

[0024] Preferably, the amount added during use is 3-20% of the total mass.

[0025] This invention uses polylactic acid and chitosan derivatives as wall materials and the aforementioned ultraviolet absorber as core material to prepare multifunctional microcapsules, which have excellent encapsulation performance, continuous and stable sustained-release effect, excellent mechanical properties, and wide applications.

[0026] The principle of this invention is as follows: (1) Chitosan is modified with octenyl succinic anhydride (OSA) to prepare a chitosan derivative with pH response; (2) Microcapsules are prepared by water / oil / water (W1 / O / W2) double emulsion method. The oil phase is mixed with deionized water and a primary emulsion of W1 / O is formed by sonication; then polyvinyl alcohol solution and emulsifier are added to the primary emulsion and a coarse heavy emulsion is prepared under mechanical stirring. After evaporating dichloromethane by heating in a 60° water bath for 3 hours, multifunctional microcapsules are prepared by centrifugation and freeze drying.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1) The prepared multifunctional microcapsules are white or grayish-white uniform spheres with an average particle size of 0.1-300 μm; moisture content ≤5%; critical stress 0-900 mN; and good mechanical properties.

[0029] 2) The prepared multifunctional microcapsules not only control the sustained release rate of the core material through the encapsulation of the inner shell layer, but also improve the impact resistance and chemical resistance of the microcapsules through the outer shell layer, ensuring the quality stability and storage stability of the product.

[0030] 3) The preparation method of multifunctional microcapsules can be used to encapsulate a variety of active substances, and the raw materials are widely available and the shell material is inexpensive;

[0031] 4) The preparation process is simple, and the produced multifunctional microcapsules can be used in pharmaceuticals, cosmetics and other fields, and can also be widely used in the field of functional materials, thus broadening the scope of application of microcapsules. Attached Figure Description

[0032] Figure 1 Infrared spectra of chitosan, octenyl succinic anhydride, and chitosan derivatives;

[0033] Figure 2 Microscopic morphology of multifunctional microcapsules;

[0034] Figure 3 This is a particle size distribution diagram of multifunctional microcapsules;

[0035] Figure 4 This is a release curve of the multifunctional microcapsules in the release medium;

[0036] Figure 5 The release curve of the multifunctional microcapsules in air. Detailed Implementation

[0037] The invention will be further illustrated below through specific embodiments, and the beneficial effects of the invention will be further demonstrated through experiments. However, these embodiments are for illustrative purposes only and are not intended to limit the invention.

[0038] A multifunctional microcapsule is prepared in the following weight parts array:

[0039]

[0040] The preparation method of the multifunctional microcapsules includes the following steps: dissolving polylactic acid and core material in a first solvent; adding chitosan derivative to a second solution to form a chitosan derivative solution; adding polyvinyl alcohol to a third solution to form a polyvinyl alcohol solution; then adding the chitosan derivative solution and a polyvinyl alcohol solution of equal volume (1:1 mass ratio) to the chitosan derivative solution to the polylactic acid / core material solution, and ultrasonically treating with an ultrasonic power of 250W for 20 minutes to obtain a primary emulsion; then adding the remaining polyvinyl alcohol solution and emulsifier to the primary emulsion, emulsifying at a speed of 2000 r / min for 45 minutes, and after emulsification, stirring at a speed of 200 r / min for 3 hours in a 60° water bath to evaporate the first solvent to prepare multifunctional microcapsules; after completion, washing three times with deionized water in a centrifuge at 4000 r / min, and finally freeze-drying in a freeze dryer for 72 hours to obtain multifunctional microcapsules.

[0041] Preferably, the mass ratio of polylactic acid to the core material can be 1:0.5, 1:1, or 1:2.

[0042] The chitosan derivative can be prepared by the following steps: 1g of chitosan is mixed with 100ml of 5wt% acetic acid solution, and after the chitosan is fully dissolved, 100ml of anhydrous ethanol is added for dilution; 0.6g of octenyl succinic anhydride (OSA) is dissolved in 13ml of anhydrous ethanol until the solution is clear; finally, the OSA solution is slowly added dropwise to the chitosan solution, and the mixture is stirred at 200r / min in a 40° water bath. After reacting for 4h, the pH of the solution is adjusted to 7.5, the precipitate is separated by centrifugation, and after drying, the chitosan derivative with pH response function is obtained.

[0043] The reaction equation for chitosan and octenyl succinic anhydride is as follows:

[0044]

[0045] Infrared spectra of chitosan, octenyl succinic anhydride, and chitosan derivatives are shown below. Figure 1 As shown. This chitosan derivative decomposes at pH less than 7, thereby accelerating the release of the core material and achieving pH-responsive targeted release. For example, it can be used as a component of pharmaceuticals or cosmetics; when applied to the human body, it accelerates the release of the core material after sweating (which is acidic); it can also be used as a functional material additive, accelerating the release of the core material in acidic environments.

[0046] The performance characterization methods of the multifunctional microcapsules prepared in this invention are as follows: Appearance test: observation and recording under natural light, optical microscope, scanning electron microscope (SEM, Nova NanoSEM 450); Infrared spectroscopy: Fourier transform infrared spectrometer (FTIR, Bruker 550); Average particle size: Malvern particle size analyzer; Critical stress was determined using a microcontroller system (Model 403A); Moisture measurement was performed according to GB / T 6283-1986.

[0047] Example 5

[0048] The raw material formulation for the microcapsules used for ultraviolet absorption is shown in the table below.

[0049] Component Parts by weight Polylactic acid (4060D, purity ≧ 95%) 1 First solvent: dichloromethane 21.25 Chitosan derivative 0.35 Second solvent: acetic acid 35 Benzophenone 2 Emulsifier: gum arabic powder 13 Polyvinyl alcohol (PVA-1788) 1 Third solvent: deionized water 110

[0050] The preparation method comprises the following steps:

[0051] Polylactic acid (PLA) and benzophenone (BPK) were dissolved in 21.25 parts of dichloromethane at a ratio of 1:2 to form a PLA / benzophenone solution. Chitosan derivatives were added to acetic acid to form a chitosan derivative solution. Polyvinyl alcohol (PVA) was added to deionized water to form a PVA solution. Subsequently, the chitosan derivative solution and an equal volume of PVA solution were added to the PLA / benzophenone solution, and the mixture was ultrasonically treated with a power of 250W for 20 minutes to obtain a primary emulsion. Then, PVA solution and gum arabic powder were added to the primary emulsion, and emulsified at 2000 rpm for 45 minutes. After emulsification, the mixture was stirred in a 60° water bath at 200 rpm for 3 hours to evaporate the dichloromethane and prepare multifunctional microcapsules. After completion, the microcapsules were washed three times with deionized water in a centrifuge at 4000 rpm, and finally freeze-dried in a freeze dryer for 72 hours to obtain the multifunctional microcapsules.

[0052] After testing, such as Figures 2-4 As shown, the average particle size of the multifunctional microcapsules is 10 ± 0.05 micrometers, and the critical stress is 5–50 mN.

[0053] Product specifications: This multifunctional microcapsule can maintain the release of benzophenone in the air for more than 3 months; it can maintain the release control for more than 72 hours in a sustained-release medium; and it retains the oil-absorbing properties.

[0054] Example 6

[0055] A skincare product for reducing UV damage, comprising the following components in parts by weight:

[0056] Component Parts by weight Propylene glycol 2.5 Hydroxybenzoate ester 0.15 Multifunctional microcapsule 0.15 Sodium hydroxide (20% concentration by weight / volume) 0.32 Glycerin stearate 4 Propyl p-hydroxybenzoate 0.1 Deionized water 90.78

[0057] The multifunctional microcapsule is the sample obtained in Example 5.

[0058] A method for preparing a skincare product that reduces UV damage includes the following steps: First, methylparaben is dispersed in propylene glycol and heated until dissolved to form an oil phase; then, it is added to deionized water at 45℃-50℃ and heated to 75℃-80℃, and sodium hydroxide is added; glyceryl stearate, glyceryl stearate, and propylparaben are mixed and heated to 70℃-75℃. The above-prepared aqueous solution is slowly added to the oil phase, maintaining the temperature at 75℃, and cooling begins after 20 minutes. At 45℃, multifunctional microcapsules are added and mixed evenly. Cooling yields a gentle, natural skincare lotion with sustained UV absorption. Testing showed that when this skincare lotion is applied to a glass slide and placed in air, UV absorption and oil absorption can be sustained for more than 10 days.

[0059] Example 7

[0060] A cold cream that reduces UV damage and absorbs skin oils is prepared from the following components in parts by weight:

[0061] Component Parts by weight Stearic acid 15 Glycerin monostearate 1 White oil 1 Cetyl alcohol 1 Propylene glycol 10 KOH 0.6 NaOH 0.05 Multifunctional microcapsule 0.6 Preservative 0.2 Water 70.75

[0062] A method for preparing a cold cream that reduces UV damage and absorbs skin oil includes the following steps: Stearic acid, glyceryl monostearate, white oil, cetyl alcohol, and propylene glycol are weighed according to the formula and added to a beaker. The mixture is then heated to 90°C to melt the materials and mix thoroughly. Next, water and alkali (KOH and NaOH) are weighed and added to the beaker to dissolve. This solution is then added to the melted material at 300 rpm. When the temperature drops to 50°C, a preservative is added. When the temperature drops to 40°C, emulsification is performed for 10 minutes using an emulsifier at 6000 rpm. After emulsification, the pH of the cream is adjusted to the required range (6.5-7.5). Finally, multifunctional microcapsules are added and mixed thoroughly. Testing showed that when this skin cream is applied to a glass slide and placed in air, UV absorption and oil absorption can be sustained for more than 30 days. (See attached image.) Figure 5 As shown, the microcapsules can be released into the air for more than 80 days.

[0063] The preferred embodiments of the present invention have been described in detail above. These are the results of numerous experiments conducted by the inventors with considerable human, financial, and time investment. It should be understood that those skilled in the art can make many modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims of this application.

Claims

1. A multifunctional microcapsule, characterized in that, It is made from an array of the following weight parts: Polylactic acid 0.8-1.2 Chitosan derivatives 0.1-0.5 Polyvinyl alcohol 0.5-1.5 Core material 0.4-2.4 Emulsifier 10-15 First solvent 20-22 Second solvent 30-50 The third solvent is 80-120; The chitosan derivative is prepared by the following steps: 1g of chitosan is mixed with 100ml of 5wt% acetic acid solution, and after the chitosan is fully dissolved, 100ml of anhydrous ethanol is added for dilution; 0.2-1.0g of octenyl succinic anhydride is dissolved in 10-15ml of anhydrous ethanol until the solution is clear; finally, the octenyl succinic anhydride solution is slowly added dropwise to the chitosan solution, and the mixture is stirred at 200r / min in a 40℃ water bath for 4h. After the reaction is carried out, the pH of the solution is adjusted to 7-8, the precipitate is separated by centrifugation and dried. The emulsifier is one or more of the following: lecithin, lanolin, gum arabic, N-dodecyl dimethylamine, quaternary ammonium salt, fatty acid soap, alkyl sulfate, alkylbenzene sulfonate, and phosphate. The first solvent is one or more of dichloromethane, n-butyl acetate, xylene, and chloroform; the second solvent is one or more of hydrochloric acid, acetic acid, and peracetic acid; and the third solvent is deionized water.

2. The multifunctional microcapsule according to claim 1, characterized in that, The core material is one or more of the following: aminobenzoic acid, benzophenone, phenyl salicylate, ethylhexyl salicylate, humosalilate, 4-hydroxybenzophenone, p-methoxycinnamate isoamyl ester, benzophenone-3, 4-methylbenzyl camphor, PABA ethylhexyl ester, methoxycinnamate ethylhexyl ester, 2-cyano-3,3-diphenylacrylate-2-ethylhexyl ester, and butyl methoxydibenzoylmethane.

3. A method for preparing a multifunctional microcapsule according to any one of claims 1-2, characterized in that, It includes the following steps: dissolving polylactic acid and a core material in a first solvent to form a polylactic acid / core material solution; adding a chitosan derivative to a second solvent to form a chitosan derivative solution; and adding polyvinyl alcohol to a third solvent to form a polyvinyl alcohol solution. Subsequently, a chitosan derivative solution and an equal volume of polyvinyl alcohol solution were added to a polylactic acid / core material solution, and ultrasonically treated with an ultrasonic power of 200-250W for 15-30 minutes to obtain a primary emulsion. Then, the remaining polyvinyl alcohol solution and emulsifier were added to the primary emulsion, and emulsified at a speed of 1500-2000 r / min for 30-45 minutes. After emulsification, the primary solvent was evaporated in a 45-60° water bath at a speed of 200-400 r / min for 3 hours to prepare multifunctional microcapsules. After completion, the microcapsules were washed three times with deionized water in a centrifuge at 4000-6000 r / min, and finally freeze-dried for 48-72 hours.

4. The application of the multifunctional microcapsule according to claim 1 as a functional additive in pharmaceuticals, cosmetics and functional materials.

5. The application of the multifunctional microcapsule according to claim 4 as a functional additive in pharmaceuticals, cosmetics and functional materials, wherein the amount added is 0.1-20% of the total mass.

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