Multilayer microcapsule and preparation method thereof

Abstract

The invention discloses a multi-layer microcapsule which sequentially comprises a central layer, a dextrin layer, a filling layer and a chitosan layer from inside to outside, the central layer contains a releaser. And the filling layer contains sodium alginate. According to the preparation method, released substances are coated with dextrin, sodium alginate and chitosan in sequence to form a multilayer microcapsule structure, the microcapsule is large in particle size and good in slow release performance, and the mechanical property is also well improved.

Description

Technical Field

[0001] The present invention relates to the field of chemistry, and more particularly to a multi-layer microcapsule. Background Art

[0002] Microcapsules generally encapsulate the released substances, thereby protecting or slow-releasing the released substances. Generally, microcapsules are small in size, and the released substances are also small, which cannot achieve long-term release. For example, in soap, shampoo, shower gel, laundry detergent and other care and cleaning products, when long-lasting fragrance is required, large-volume microcapsules are very necessary. However, the microcapsules in the prior art are all single-layered, and the formation of microcapsules is emulsified. When a large microcapsule is formed, the shell is often easily broken. Summary of the invention

[0003] In view of the shortcomings of the prior art, the object of the present invention is to provide a multilayer microcapsule.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A multilayer microcapsule,

[0006] From inside to outside, they include:

[0007] Central layer, dextrin layer, filling layer, chitosan layer;

[0008] The core layer contains the release substance.

[0009] The filling layer contains sodium alginate.

[0010] Step 1: emulsifying the released substance to obtain a homogeneous emulsion;

[0011] Step 2: prepare a dextrin solution, add the homogeneous emulsion into the dextrin solution, stir in a constant temperature water bath, wash, filter and dry to obtain dextrin microcapsules;

[0012] Step 3: preparing chitosan solution;

[0013] Step 4: Prepare sodium alginate solution;

[0014] Step 5: Dissolve the dextrin microcapsules in water and add them to the sodium alginate solution, stir, absorb the mixed solution, and inject it into the calcium chloride solution to obtain white microspheres;

[0015] Step 6: Add the white microspheres into the chitosan solution, stir, filter, and dry to obtain multilayer microcapsules.

[0016] As a further improvement of the present invention,

[0017] The step 1 is specifically as follows:

[0018] The release substance and the surfactant are mixed, water is added, and the mixture is stirred at a stirring rate of 5000 to 15000 r / min for 10 to 30 minutes to obtain a homogeneous emulsion.

[0019] As a further improvement of the present invention,

[0020] The step 2 is specifically as follows:

[0021] Dissolve dextrin in 50-80°C water to obtain a dextrin solution, then slowly add the homogeneous emulsion under stirring, slowly stir at 40-70°C for 2-5 hours, then wash with anhydrous ethanol, filter, and rotary evaporate and dry at 40°C to obtain dextrin microcapsules.

[0022] As a further improvement of the present invention,

[0023] The step three is specifically as follows:

[0024] Chitosan was dissolved in water, acetic acid was added at 40°C while stirring, and the pH value was adjusted to between 5 and 6 to obtain a chitosan solution.

[0025] As a further improvement of the present invention,

[0026] The step 4 is specifically as follows:

[0027] Dissolve sodium alginate in water, stir at 40-50°C until completely dissolved, and cool to room temperature;

[0028] The step five is specifically as follows:

[0029] Dissolve the dextrin microcapsules obtained in step 2 in water and mix with the sodium alginate solution obtained in step 4, and stir at a speed of 100-200 r / min for 5-20 hours. Use a syringe to draw the mixed solution and inject it into a 2% calcium chloride solution and stir for 10-60 minutes to obtain white microspheres.

[0030] As a further improvement of the present invention,

[0031] The sodium alginate is modified sodium alginate, and the preparation method of the sodium alginate is as follows:

[0032] Sodium alginate and aminononanoic acid were dissolved in water, reacted at 120° C. under microwave for 30 min, washed with acetone after cooling, and dried in an oven at 60° C. for 24 h to obtain modified sodium alginate.

[0033] As a further improvement of the present invention,

[0034] The dextrin is modified dextrin;

[0035] The modified dextrin preparation method is:

[0036] Take β-cyclodextrin and phthalic anhydride and dissolve them in DMF, heat to 80°C, stir for 10 hours, cool and add 60 mL of dichloromethane to obtain a white precipitate, wash the precipitate with acetone, and dry it in an oven at 60°C for 24 hours to obtain acid-modified dextrin.

[0037] As a further improvement of the present invention,

[0038] The chitosan is amino-modified chitosan

[0039] Chitosan and aminononanoic acid were dissolved in water, reacted at 120° C. under microwave for 30 min, washed with acetone after cooling, and dried in an oven at 60° C. for 24 h to obtain amino-modified chitosan.

[0040] The beneficial effects of the present invention are as follows: the released substance is coated with dextrin, sodium alginate and chitosan in sequence to form a multi-layer microcapsule structure; the microcapsule has a larger particle size, better sustained-release performance and better improved mechanical properties. DETAILED DESCRIPTION

[0041] Embodiment 1:

[0042] A multilayer microcapsule,

[0043] From inside to outside, they include:

[0044] Central layer, dextrin layer, filling layer, chitosan layer;

[0045] The core layer contains the release substance.

[0046] The filling layer contains sodium alginate.

[0047] Step 1: Mix 0.3 g of oil-soluble essence (green tea), 0.1 g of fatty alcohol ether sulfate (AES) and 0.1 g of fatty alcohol polyoxyethylene ether (AEO-9), add 2 g of double distilled water, stir for 15 min at a stirring rate of 10000 r / min to obtain a homogeneous emulsion.

[0048] Step 2: Dissolve 1.2 g of β-cyclodextrin in 6.8 g of double distilled water at 70°C to obtain a dextrin solution, then slowly add the homogeneous emulsion under stirring, slowly stir at 50°C for 4 hours, then wash with anhydrous ethanol, filter, and rotary evaporate and dry at 40°C to obtain dextrin microcapsules.

[0049] Step 3: Take 1g of chitosan and dissolve it in 100ml of distilled water, add 36% acetic acid (about 2ml) at 40°C while stirring, adjust the pH value to 5, and obtain a chitosan solution.

[0050] Step 4: Dissolve 2 g of sodium alginate in 200 ml of water, stir at 40 °C until completely dissolved, and cool to room temperature;

[0051] Step 5: Dissolve 2 g of dextrin microcapsules obtained in step 2 in water and mix with the sodium alginate solution obtained in step 4, and stir at a speed of 170 r / min for 10 h. Use a syringe to draw the mixed solution and inject it into a 2% calcium chloride solution and stir for 30 min to obtain white microspheres.

[0052] Step 6: Add the white microspheres into the chitosan solution and stir for 1 hour, filter and dry to obtain multilayer microcapsules.

[0053] Embodiment 2:

[0054] Preparation of modified dextrin:

[0055] Take 6g of β-cyclodextrin and 7.5g of phthalic anhydride and dissolve them in 30ml of DMF, heat to 80℃, stir for 10h, cool and add 60mL of dichloromethane to obtain a white precipitate. The precipitate is washed with acetone and dried in an oven at 60℃ for 24h to obtain acid-modified dextrin.

[0056] Embodiment three:

[0057] Preparation of modified chitosan:

[0058] Take 10g chitosan and 7.5g phthalic anhydride and dissolve them in 30ml DMF, heat to 80℃, stir for 10h, cool and add 60mL dichloromethane to obtain white precipitate, wash the precipitate with acetone, and dry it in an oven at 60℃ for 24h to obtain modified chitosan.

[0059] Embodiment 4:

[0060] Preparation of modified sodium alginate:

[0061] 10 g of sodium alginate and 5 g of aminononanoic acid were dissolved in 30 ml of water, reacted at 120° C. under microwave for 30 min, washed with acetone after cooling, and dried in an oven at 60° C. for 24 h to obtain modified sodium alginate.

[0062] Embodiment five:

[0063] A multilayer microcapsule,

[0064] From inside to outside, they include:

[0065] Central layer, dextrin layer, filling layer, chitosan layer;

[0066] The core layer contains the release substance.

[0067] The filling layer contains sodium alginate.

[0068] Step 1: Mix 0.3 g of oil-soluble essence (green tea), 0.1 g of fatty alcohol ether sulfate (AES) and 0.1 g of fatty alcohol polyoxyethylene ether (AEO-9), add 2 g of double distilled water, stir for 15 min at a stirring rate of 10000 r / min to obtain a homogeneous emulsion.

[0069] Step 2: Dissolve 1.5 g of the modified dextrin prepared in Example 2 in 6.8 g of double distilled water at 70°C to obtain a dextrin solution, then slowly add the homogeneous emulsion under stirring, slowly stir at 50°C for 4 hours, then wash with anhydrous ethanol, filter, and rotary evaporate and dry at 40°C to obtain dextrin microcapsules.

[0070] Step 3: Take 1.5 g of the modified chitosan prepared in Example 3 and dissolve it in 100 ml of distilled water. Add 36% acetic acid (about 2 ml) at 40° C. while stirring, and adjust the pH value to 5 to obtain a chitosan solution.

[0071] Step 4: Take 2 g of the sodium alginate prepared in Example 4 and dissolve it in 200 ml of water, stir at 40° C. until it is completely dissolved, and cool to room temperature;

[0072] Step 5: Dissolve 2 g of dextrin microcapsules obtained in step 2 in water and mix with the sodium alginate solution obtained in step 4, and stir at a speed of 170 r / min for 10 h. Use a syringe to draw the mixed solution and inject it into a 2% calcium chloride solution and stir for 30 min to obtain white microspheres.

[0073] Step 6: Add the white microspheres into the chitosan solution and stir for 1 hour, filter and dry to obtain multilayer microcapsules.

[0074] Ingredients:

[0075] raw material factory Oil-soluble flavor (tea) Guangzhou Kejin Biotechnology Co., Ltd. Fatty alcohol polyoxyethylene ether (AEO-9) Shandong Jubang Chemical Co., Ltd. β-Cyclodextrin Jiangsu Ruiduo Bioengineering Co., Ltd. Ethanol Shandong Luying Chemical Co., Ltd. Chitosan Shaanxi Rankang Biotechnology Co., Ltd. Acetic acid Wuhan Xinghengtai Chemical Co., Ltd. Sodium alginate Anhui Zhonghong Bioengineering Co., Ltd. Calcium chloride Qingdao Zhongsheng Meibang Chemical Technology Co., Ltd. Phthalic anhydride Shandong Jinhe Chemical Co., Ltd. DMF Jinan Century Tongda Chemical Co., Ltd. Dichloromethane Jinan Xichuan Chemical Technology Co., Ltd. acetone Maoming Runjing Chemical Co., Ltd. Amino nonanoic acid Hubei Wonder Chemical Co., Ltd.

[0076] test:

[0077] 1. Particle size measurement: Take ten microspheres and measure them and take the average value

[0078] 2. Hardness test:

[0079] The mechanical properties of the microcapsules were determined by using a MF-WSF1 micromanipulator (MF-WSF1, Changzhou, China) to compress a single microcapsule between two parallel surfaces consisting of a force sensor probe and a sample stage, and to measure the force and deformation when the microcapsule ruptured at a preset speed.

[0080] Compression experiments include compression fracture tests and compression-hold tests. In a representative compression fracture test, 30 microcapsules were compressed to fracture by the force applied by the probe, and then the fracture force and displacement data were obtained from the force-displacement curve. The diameter (d) of the microcapsule can be obtained directly from the side-view optical image. In a typical compression-hold test, microcapsules with a particle size of 15um were selected and then compressed to 6.3%, 12.5% ​​and 18.8% at a speed of 2μm / s for 10s to observe the change in force. In these operations, the force applied to the microcapsule was simultaneously measured by a force sensor (Model 403A, AuoraScienti@c, Canada). Hardness analysis of microcapsules, the hardness of the microcapsules can be obtained by the slope of the linear plastic region of the force-displacement curve, which is obtained by using the equation.

[0081] F=2πHRδ

[0082] Where F is the applied force, R is the diameter, and δ is the displacement.

[0083] 3. Fragrance experiment: Place the microspheres and pure essence in a beaker and seal it with plastic wrap. Subjectively evaluate the fragrance (1-10) after 1h, 4h, 12h, 24h, 2days, and 4days.

[0084] Table 1: Particle size and hardness test results

[0085] Particle size hardness Embodiment 1 12.5μm 2.72MPa Embodiment 5 11.2μm 4.01MPa

[0086] Table 2:

[0087] Fragrance test (25℃)

[0088] essence Example 1 Microspheres Example 5 Microspheres 1h 9 7 7 4h 7 6 6 12h 5 6 6 24h 3 5 5 2day 2 5 5 4day 1 4 4

[0089] Table 3:

[0090] Fragrance test (50℃)

[0091]

[0092]

[0093] The present invention mainly forms a multi-layer microcapsule structure by coating the released substance with dextrin, sodium alginate and chitosan in sequence. The microcapsule has a larger particle size, better sustained-release performance and better improved mechanical properties.

[0094] Both Example 1 and Example 5 exhibit good sustained-release performance, and after using modified dextrin, modified sodium alginate, and modified chitosan in Example 5, the hardness is further improved, and it also has a better sustained-release effect at high temperature. This effect is brought about because the modified dextrin and modified chitosan have carboxyl groups on their surfaces, and the modified sodium alginate has amino groups. The amino groups and carboxyl groups have strong adsorption capacity, so that the multilayer microcapsules have better mechanical properties and high temperature resistance.

[0095] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A multilayer microcapsule, characterized in that: From inside to outside, they include: Central layer, dextrin layer, filling layer, chitosan layer; The core layer contains the release substance.

2. The filling layer contains sodium alginate.

3. A method for preparing multilayer microcapsules, characterized in that: Step 1: emulsifying the release material to obtain a homogeneous emulsion; Step 2: prepare a dextrin solution, add the homogeneous emulsion into the dextrin solution, stir in a constant temperature water bath, wash, filter and dry to obtain dextrin microcapsules; Step 3: preparing chitosan solution; Step 4: Prepare sodium alginate solution; Step 5: Dissolve the dextrin microcapsules in water and add them to the sodium alginate solution, stir, absorb the mixed solution, and inject it into the calcium chloride solution to obtain white microspheres; Step 6: Add the white microspheres into the chitosan solution, stir, filter, and dry to obtain multilayer microcapsules.

4. The method for preparing a multilayer microcapsule according to claim 2, characterized in that: The step 1 is specifically as follows: The release substance and the surfactant are mixed, water is added, and the mixture is stirred at a stirring rate of 5000-15000 r / min for 10-30 minutes to obtain a homogeneous emulsion.

5. The method for preparing a multilayer microcapsule according to claim 2, characterized in that: The step 2 is specifically as follows: Dissolve dextrin in 50-80°C water to obtain a dextrin solution, then slowly add the homogeneous emulsion under stirring, slowly stir at 40-70°C for 2-5 hours, then wash with anhydrous ethanol, filter, and rotary evaporate and dry at 40°C to obtain dextrin microcapsules.

6. The method for preparing a multilayer microcapsule according to claim 2, characterized in that: The step three is specifically as follows: Chitosan was dissolved in water, acetic acid was added at 40°C while stirring, and the pH value was adjusted to between 5 and 6 to obtain a chitosan solution.

7. The method for preparing a multilayer microcapsule according to claim 2, characterized in that: The step 4 is specifically as follows: Dissolve sodium alginate in water, stir at 40-50°C until completely dissolved, and cool to room temperature; The step five is specifically as follows: The dextrin microcapsules obtained in step 2 are dissolved in water and mixed with the sodium alginate solution obtained in step 4, and stirred at a speed of 100-200 r / min for 5-20 hours. The mixed solution is drawn into a 2% calcium chloride solution with a syringe and stirred for 10-60 minutes to obtain white microspheres.

8. The method for preparing a multilayer microcapsule according to claim 2, characterized in that: The sodium alginate is modified sodium alginate, and the preparation method of the sodium alginate is as follows: Sodium alginate and aminononanoic acid were dissolved in water, reacted at 120° C. under microwave for 30 min, washed with acetone after cooling, and dried in an oven at 60° C. for 24 h to obtain modified sodium alginate.

9. The method for preparing a multilayer microcapsule according to claim 2, characterized in that: The dextrin is modified dextrin; The modified dextrin preparation method is: Take β-cyclodextrin and phthalic anhydride and dissolve them in DMF, heat to 80°C, stir for 10 hours, cool and add 60 mL of dichloromethane to obtain a white precipitate. The precipitate is washed with acetone and dried in an oven at 60°C for 24 hours to obtain modified dextrin.

10. The method for preparing a multilayer microcapsule according to claim 2, characterized in that: The chitosan is modified chitosan. Chitosan and phthalic anhydride are dissolved in DMF, heated to 80° C., stirred for 10 h, cooled, and 60 mL of dichloromethane is added to obtain a white precipitate. The precipitate is washed with acetone and dried in an oven at 60° C. for 24 h to obtain modified chitosan.

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