Preparation method of eucommia gum microspheres, eucommia gum microspheres and applications

Abstract

The invention discloses a preparation method of eucommia gum microspheres, eucommia gum microspheres and applications. The method comprises: (1) dissolving eucommia gum in a low-boiling point organic solvent to obtain eucommia gum liquid; (2) centrifuging the eucommia gum liquid to remove impurities to form an oil phase; (3) dissolving a water-soluble emulsifier in deionized water to form an aqueous phase; (4) adding the oil phase to the aqueous phase, emulsifying to obtain a eucommia liquid dispersion; (5) evaporating the eucommia liquid dispersion to remove the organic solvent to obtain a microsphere dispersion; (6) centrifuging the microsphere dispersion, washing, removing the emulsifier remaining on the microspheres, and drying to obtain the eucommia gum microspheres. The invention prepares eucommia gum into microspheres with adjustable particle sizes ranging from hundreds of nanometers to tens of micrometers. The microspheres have a regular shape and a narrow particle size distribution, so that the eucommia gum can be uniformly dispersed in gutta-percha as a filler.

Description

Technical Field

[0001] The invention relates to the technical field of preparation and application of polymer microspheres, and in particular to a preparation method of eucommia gum microspheres, the eucommia gum microspheres and applications. Background Art

[0002] Eucommia gum is a bio-based polymer material with rubber and plastic duality synthesized in Eucommia ulmoides, a unique economic tree species in my country. Its main chemical component is trans-1,4-polyisoprene, which is an isomer of cis-1,4-polyisoprene, the main chemical component of natural rubber produced from Hevea brasiliensis. The unique chemical structure makes Eucommia gum easy to crystallize at room temperature, forming two crystal forms, α and β, with melting temperatures of about 58°C and 52°C respectively.

[0003] Due to its good biocompatibility, volume stability and low melting temperature, eucommia gum is often used in dentistry as the base material of gutta-percha, the most widely used main material for root canal filling. In the process of using gutta-percha tips for root canal filling treatment, in order to make the root canal tightly sealed, the gutta-percha tips are usually used in combination with root canal sealers. The function of the root canal sealer is to fill the gap between the gutta-percha tip and the inner wall of the root canal and the irregular apical area. Adding eucommia gum particles to the sealer can make the filling material in the irregular apical area contain gutta-percha components, thereby reducing the occurrence of apical microleakage, improving the tightness of root canal filling, and can also make the root canal sealer and gutta-percha combined into one, so that it has a strong affinity with the gutta-percha tip and dentin. However, the particle size of the existing eucommia gum particles is about 30 μm, and the shape is irregular, which affects the amount of eucommia gum particles added to the root canal sealer and weakens the ability of the eucommia gum particles to enter the irregular apical area. If eucommia gum can be made into nanoscale microspheres with regular shapes and uniform particle size distribution, its role in root canal sealers can be further enhanced.

[0004] Therefore, providing a kind of eucommia gum microparticles with smaller particle size, regular shape and more uniform size is a problem that needs to be solved at present. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a preparation method of eucommia gum microspheres, eucommia gum microspheres and applications. The present invention prepares eucommia gum into microspheres with adjustable particle sizes ranging from hundreds of nanometers to tens of micrometers, and the microspheres have regular shapes and narrow particle size distribution, so that the eucommia gum can be uniformly dispersed in gutta-percha as a filler.

[0006] One of the purposes of the present invention is to provide a method for preparing eucommia gum microspheres.

[0007] The method comprises:

[0008] (1) dissolving eucommia gum in a low-boiling point organic solvent to obtain eucommia gum liquid;

[0009] (2) centrifuging the eucommia gum solution to remove impurities and form an oil phase;

[0010] (3) dissolving a water-soluble emulsifier in deionized water to form an aqueous phase;

[0011] (4) adding the oil phase to the water phase under low-speed stirring, and then emulsifying at high speed to obtain a rubber dispersion;

[0012] (5) evaporating the gel dispersion to remove the organic solvent to obtain a microsphere dispersion;

[0013] (6) centrifuging and washing the microsphere dispersion to remove the residual emulsifier on the microspheres, and drying to obtain the eucommia gum microspheres.

[0014] In a preferred embodiment of the present invention,

[0015] In step (1),

[0016] The eucommia gum is one or a combination of eucommia gum, gutta-percha, balata gum and euonymus gum;

[0017] The low boiling point organic solvent is dichloromethane;

[0018] The mass ratio of the low boiling point organic solvent to eucommia gum is (10-100):1, preferably (15-100):1;

[0019] The dissolution temperature is 25-30°C and the dissolution time is 4-6h.

[0020] In a preferred embodiment of the present invention,

[0021] In step (2),

[0022] After the eucommia gum liquid is centrifuged to remove impurities, an oil-soluble emulsifier is added to form an oil phase;

[0023] The oil-soluble emulsifier is one or a combination of polyoxyethylene ether and polyoxyethylene fatty alcohol ether;

[0024] The amount of the oil-soluble emulsifier used is 1-5% of the mass of the oil phase, preferably 1%-2%.

[0025] In a preferred embodiment of the present invention,

[0026] In step (3),

[0027] The water-soluble emulsifier is polyvinyl alcohol;

[0028] The amount of polyvinyl alcohol used is 0.5% to 5% of the mass of the water phase, preferably 0.7% to 2%, and more preferably 0.8% to 1%;

[0029] The dissolving temperature is 50~70℃.

[0030] In a preferred embodiment of the present invention,

[0031] In step (3),

[0032] Sodium dodecylbenzene sulfonate or sodium dodecyl sulfonate, preferably sodium dodecylbenzene sulfonate, can also be added to the water-soluble emulsifier, and the pH value of the aqueous phase is adjusted to 10-13 with alkali solution;

[0033] The mass ratio of sodium dodecylbenzene sulfonate or sodium dodecyl sulfonate to polyvinyl alcohol is (0.5-2):1;

[0034] The alkali solution is one of potassium hydroxide aqueous solution, sodium hydroxide aqueous solution and ammonia water, and the mass concentration of the alkali solution is 10% to 30%.

[0035] In a preferred embodiment of the present invention,

[0036] In step (4),

[0037] The oil-water ratio of the oil phase to the water phase is 1:(1-4), preferably 1:(1.5-2);

[0038] The low speed is 2000-4000r / min, and the high speed is 8000-10000r / min;

[0039] The emulsification time is 5 to 20 minutes.

[0040] In a preferred embodiment of the present invention,

[0041] In step (5),

[0042] The evaporation method is normal pressure evaporation, and the evaporation temperature is 30-40℃.

[0043] In a preferred embodiment of the present invention,

[0044] In step (6),

[0045] The centrifugal speed is 5000-10000 r / min, preferably 5000-8000 r / min, and the centrifugal time is 10-20 min;

[0046] The drying temperature is 30 to 55° C., preferably 40 to 50° C., and the drying time is 18 to 24 hours.

[0047] The second object of the present invention is to provide a kind of eucommia gum microspheres obtained by the preparation method of one of the objects of the present invention.

[0048] The average particle size of the eucommia gum microspheres is 200nm-20μm, preferably 500nm-11μm.

[0049] The third object of the present invention is the use of the eucommia gum microspheres of the second object of the present invention as a gutta-percha filling material.

[0050] The specific technical solutions of the present invention may be as follows:

[0051] The preparation method of the eucommia gum microspheres preferably comprises the following steps:

[0052] (1) Dissolving eucommia gum in a low-boiling point organic solvent at a certain temperature to obtain eucommia gum liquid.

[0053] (2) centrifuging the eucommia gum solution obtained in step (1) to remove impurities in the gum solution, and then dissolving an oil-soluble emulsifier in the eucommia gum solution after impurities removal to form an oil phase.

[0054] (3) Dissolve the water-soluble emulsifier in deionized water under heating and stirring conditions to form an aqueous phase.

[0055] (4) under the stirring action of the homogenizer at a low speed, the oil phase is slowly added to the water phase according to a certain oil-water ratio. After the oil phase is completely added, the homogenizer is adjusted to a higher speed for emulsification for a period of time to obtain a rubber dispersion;

[0056] (5) The colloid dispersion is heated and stirred at a certain temperature to evaporate and remove the organic solvent, and a microsphere dispersion is obtained after the liquid level stops dropping.

[0057] (6) The microsphere dispersion is centrifuged to remove the emulsifier aqueous solution, and then deionized water is added for washing and centrifugation. The washing and centrifugation are repeated several times to remove the residual emulsifier on the eucommia gum microspheres. The microspheres with the emulsifier removed are placed in an oven and dried at a certain temperature to obtain eucommia gum microspheres.

[0058] In step (1), the eucommia gum is dissolved by heating in a water bath, and a stirring paddle is used for stirring during the dissolution process, and the rotation speed of the stirring paddle is 300-400 r / min.

[0059] In step (2), the centrifuge speed required to remove insoluble impurities in the eucommia gum solution is 10000-16000 r / min, and the centrifugation time is 20-40 min.

[0060] In step (5), the rotation speed of the stirring paddle is 100 to 500 r / min, preferably 150 to 300 r / min;

[0061] The melting temperature of Eucommia gum is relatively low, about 55°C. When the temperature of the solvent evaporation is higher than the melting temperature of Eucommia gum, the dispersed solid Eucommia gum microspheres will be in a molten state. During the stirring process, the molten Eucommia gum microspheres will collide and adhere to each other, causing the Eucommia gum to condense and precipitate. Therefore, it is necessary to select an organic solvent with a low boiling point so that the organic solvent can be evaporated and removed at a temperature lower than the melting temperature of Eucommia gum.

[0062] In step (6), the washing and centrifugation are repeated 3 to 5 times with deionized water; the temperature of the oven must be lower than the melting temperature of eucommia gum to prevent the obtained eucommia gum microspheres from melting and sticking; the drying time is 18 to 24 hours to ensure that the water is completely evaporated.

[0063] The beneficial effects of the present invention are as follows:

[0064] The invention prepares eucommia gum microspheres through the steps of dissolving, emulsifying, evaporating, washing, drying and the like. The average particle size of the microspheres is within the range of 500nm to 11μm, which can be controlled by adjusting the formula and the preparation process as needed, and the particle size distribution is relatively narrow; the shape of the eucommia gum microspheres is a regular solid sphere with a smooth surface. The invention lays a foundation for eucommia gum with a particle size within the range of 500nm to 11μm to be uniformly dispersed in a matrix as a gutta-percha filler.

[0065] In addition, the eucommia gum of the present invention has good solubility in low-boiling point organic solvents, and because the solvent has a low boiling point and is relatively easy to volatilize, the temperature required in the steps of dissolution and solvent evaporation and removal is relatively low, which has the advantages of energy saving and time saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 The eucommia gum microsphere sample of Example 1;

[0067] Figure 2 This is a SEM image of the eucommia gum microspheres of Example 1 magnified 400 times;

[0068] Figure 3 This is a SEM image of the eucommia gum microspheres of Example 1 magnified 2000 times;

[0069] Figure 4 The particle size statistics of the eucommia gum microspheres of Example 1;

[0070] Figure 5 The particle size distribution diagram of the eucommia gum microspheres of Examples 2, 3, 4, and 5. DETAILED DESCRIPTION

[0071] The present invention is described in detail below in conjunction with specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0072] The raw materials used in the examples are all conventional commercially available raw materials.

[0073] The SEM images of the present invention were obtained by using a Hitachi S4800 scanning electron microscope.

[0074] The particle size of the present invention is measured by ZetaPALS Zata potential and particle size analyzer of Brookhaven Instrument Company, USA.

[0075] Example 1

[0076] A preparation method of eucommia gum microspheres

[0077] Preparation of oil phase: 10g of eucommia gum and 990g of dichloromethane were added to a three-necked flask, heated to 30°C in a water bath, the stirring speed was 300r / min, and the dissolution time was 4h. The dissolved eucommia gum solution was centrifuged at a speed of 12000r / min for 30min to remove impurities at the bottom of the centrifuge tube to form an oil phase.

[0078] Preparation of the aqueous phase: Pour 20 g of polyvinyl alcohol (1788 type) into 1980 g of deionized water, and stir at 800 r / min at 60° C. with a magnetic stirrer until the polyvinyl alcohol is completely dissolved in the water to form an aqueous phase.

[0079] Emulsification: adjust the speed of the homogenizer to 4000r / min. Under the shearing action of the homogenizer, slowly add the oil phase to the water phase. The ratio of oil phase to water phase is 1:2. After the oil phase is completely added, adjust the speed of the homogenizer to 8000r / min and continue emulsification for 10 minutes to obtain a rubber dispersion.

[0080] Evaporation: Place the emulsified gum dispersion in a three-necked flask, heat it to 40°C with a water bath, evaporate the dichloromethane while stirring with a stirring paddle at a speed of 300r / min, and use a condensation device to recover the evaporated dichloromethane. When the liquid level in the flask no longer drops or no distillate flows out of the condenser, stop evaporation to obtain a dispersion of eucommia gum microspheres.

[0081] Washing: Centrifuge the eucommia gum microsphere dispersion obtained in the previous step at a centrifuge speed of 5000r / min for 10min, remove the emulsifier aqueous solution at the bottom of the centrifuge tube, add deionized water, shake thoroughly and then centrifuge, repeat this three times to obtain a high solid content eucommia gum microsphere dispersion without emulsifier residue.

[0082] Drying: The high solid content eucommia gum microsphere dispersion without emulsifier residue is placed in an oven at 45° C. for 24 hours to completely remove moisture to obtain eucommia gum microspheres.

[0083] Example 2

[0084] A preparation method of eucommia gum microspheres

[0085] Preparation of oil phase: 50g of eucommia gum and 950g of dichloromethane were added to a three-necked flask, heated to 25°C in a water bath, the stirring speed was 400r / min, and the dissolution time was 6h. The dissolved eucommia gum solution was centrifuged at a speed of 16000r / min for 40min to remove impurities at the bottom of the centrifuge tube to form an oil phase.

[0086] Preparation of the aqueous phase: Pour 12g of polyvinyl alcohol (1788 type) and 11.25g of sodium dodecylbenzene sulfonate into 1476.75g of deionized water, stir at 60°C with a magnetic rod at 800r / min until the polyvinyl alcohol and sodium dodecylbenzene sulfonate are completely dissolved in the water to form an aqueous phase. Dissolve 20g of sodium hydroxide in 80g of water to prepare an alkaline solution, add the alkaline solution dropwise into the aqueous phase, and adjust the pH value of the solution to 10.

[0087] Emulsification, adjust the speed of the homogenizer to 4000r / min, under the shearing action of the homogenizer, slowly add the oil phase to the water phase, the ratio of oil phase to water phase is 1:1.5, after the oil phase is completely added, adjust the speed of the homogenizer to 8000r / min, continue emulsification for 5 minutes, and obtain a rubber dispersion.

[0088] Evaporation: Place the emulsified gum dispersion in a three-necked flask, heat it to 40°C with a water bath, evaporate the dichloromethane while stirring with a stirring paddle at a speed of 300r / min, and use a condensation device to recover the evaporated dichloromethane. When the liquid level in the flask no longer drops or no distillate flows out of the condenser, stop evaporation to obtain a dispersion of eucommia gum microspheres.

[0089] Washing: Centrifuge the eucommia gum microsphere dispersion obtained in the previous step at a centrifuge speed of 5000r / min for 10min, remove the emulsifier aqueous solution at the bottom of the centrifuge tube, add deionized water, shake thoroughly and then centrifuge, repeat this three times to obtain a high solid content eucommia gum microsphere dispersion without emulsifier residue.

[0090] Drying: The high solid content eucommia gum microsphere dispersion without emulsifier residue is placed in an oven at 45° C. for 24 hours to completely remove moisture to obtain eucommia gum microspheres.

[0091] Example 3

[0092] A preparation method of eucommia gum microspheres

[0093] Preparation of oil phase: 50g of eucommia gum and 950g of dichloromethane were added to a three-necked flask, heated to 30°C in a water bath, the stirring speed was 300r / min, and the dissolution time was 4h. The dissolved eucommia gum solution was centrifuged at a speed of 16000r / min for 40min to remove impurities at the bottom of the centrifuge tube to form an oil phase.

[0094] Preparation of the aqueous phase: Pour 16g of polyvinyl alcohol (1788 type) and 30g of sodium dodecylbenzene sulfonate into 1954g of deionized water, stir at 800r / min with a magnetic bar at 60°C until the polyvinyl alcohol and sodium dodecylbenzene sulfonate are completely dissolved in the water to form an aqueous phase. Dissolve 20g of sodium hydroxide in 80g of water to prepare an alkaline solution, add the alkaline solution dropwise into the aqueous phase, and adjust the pH value of the solution to 11.5.

[0095] Emulsification: adjust the speed of the homogenizer to 4000r / min. Under the shearing action of the homogenizer, slowly add the oil phase to the water phase. The ratio of oil phase to water phase is 1:2. After the oil phase is completely added, adjust the speed of the homogenizer to 8000r / min and continue emulsification for 10 minutes to obtain a rubber dispersion.

[0096] Evaporation: Place the emulsified gum dispersion in a three-necked flask, heat it to 40°C with a water bath, evaporate the dichloromethane while stirring with a stirring paddle at a speed of 300r / min, and use a condensation device to recover the evaporated dichloromethane. When the liquid level in the flask no longer drops or no distillate flows out of the condenser, stop evaporation to obtain a dispersion of eucommia gum microspheres.

[0097] Washing: Centrifuge the eucommia gum microsphere dispersion obtained in the previous step at a centrifuge speed of 5000r / min for 10min, remove the emulsifier aqueous solution at the bottom of the centrifuge tube, add deionized water, shake thoroughly and then centrifuge, repeat this three times to obtain a high solid content eucommia gum microsphere dispersion without emulsifier residue.

[0098] Drying: The high solid content eucommia gum microsphere dispersion without emulsifier residue is placed in an oven at 45° C. for 24 hours to completely remove moisture to obtain eucommia gum microspheres.

[0099] Example 4

[0100] A preparation method of eucommia gum microspheres

[0101] Preparation of oil phase: Add 50g of Eucommia gum and 950g of dichloromethane into a three-necked flask, heat to 30°C with a water bath, stir at 300r / min, and dissolve for 4h. Centrifuge the dissolved Eucommia gum solution at 16000r / min for 40min to remove impurities at the bottom of the centrifuge tube. Add 10.1g of polyoxyethylene ether to the Eucommia gum solution after impurity removal, stir with a glass rod until the polyoxyethylene ether is completely dissolved to form an oil phase.

[0102] Preparation of the aqueous phase: Pour 16g of polyvinyl alcohol (1788 type) and 30g of sodium dodecylbenzene sulfonate into 1954g of deionized water, stir at 800r / min with a magnetic bar at 60°C until the polyvinyl alcohol and sodium dodecylbenzene sulfonate are completely dissolved in the water to form an aqueous phase. Dissolve 20g of sodium hydroxide in 80g of water to prepare an alkaline solution, add the alkaline solution dropwise into the aqueous phase, and adjust the pH value of the solution to 11.5.

[0103] Emulsification: adjust the speed of the homogenizer to 4000r / min. Under the shearing action of the homogenizer, slowly add the oil phase into the water phase. The ratio of oil phase to water phase is 1:2. After the oil phase is completely added, adjust the speed of the homogenizer to 10000r / min and continue emulsification for 10 minutes to obtain a rubber dispersion.

[0104] Evaporation: Place the emulsified gum dispersion in a three-necked flask, heat it to 40°C with a water bath, evaporate the dichloromethane while stirring with a stirring paddle at a speed of 300r / min, and use a condensation device to recover the evaporated dichloromethane. When the liquid level in the flask no longer drops or no distillate flows out of the condenser, stop evaporation to obtain a dispersion of eucommia gum microspheres.

[0105] Washing: Centrifuge the eucommia gum microsphere dispersion obtained in the previous step at a centrifuge speed of 8000r / min for 20min, remove the emulsifier aqueous solution at the bottom of the centrifuge tube, add deionized water, shake thoroughly and then centrifuge, repeat this three times to obtain a high solid content eucommia gum microsphere dispersion without emulsifier residue.

[0106] Drying: The high solid content eucommia gum microsphere dispersion without emulsifier residue is placed in an oven at 45° C. for 24 hours to completely remove moisture to obtain eucommia gum microspheres.

[0107] Example 5

[0108] A preparation method of eucommia gum microspheres

[0109] Preparation of oil phase: Add 50g of Eucommia gum and 950g of dichloromethane into a three-necked flask, heat to 30°C with a water bath, stir at 300r / min, and dissolve for 4h. Centrifuge the dissolved Eucommia gum solution at 16000r / min for 40min to remove impurities at the bottom of the centrifuge tube. Add 20.4g of polyoxyethylene ether to the Eucommia gum solution after impurity removal, stir with a glass rod until the polyoxyethylene ether is completely dissolved to form an oil phase.

[0110] Preparation of the aqueous phase: Pour 16g of polyvinyl alcohol (1788 type) and 30g of sodium dodecylbenzene sulfonate into 1954g of deionized water, stir at 800r / min with a magnetic bar at 60°C until the polyvinyl alcohol and sodium dodecylbenzene sulfonate are completely dissolved in the water to form an aqueous phase. Dissolve 20g of sodium hydroxide in 80g of water to prepare an alkaline solution, add the alkaline solution dropwise into the aqueous phase, and adjust the pH value of the solution to 13.

[0111] Emulsification: adjust the speed of the homogenizer to 2000r / min. Under the shearing action of the homogenizer, slowly add the oil phase into the water phase. The ratio of oil phase to water phase is 1:2. After the oil phase is completely added, adjust the speed of the homogenizer to 8000r / min and continue emulsification for 20 minutes to obtain a rubber dispersion.

[0112] Evaporation: Place the emulsified gum dispersion in a three-necked flask, heat it to 40°C with a water bath, evaporate the dichloromethane while stirring with a stirring paddle at a speed of 300r / min, and use a condensation device to recover the evaporated dichloromethane. When the liquid level in the flask no longer drops or no distillate flows out of the condenser, stop evaporation to obtain a dispersion of eucommia gum microspheres.

[0113] Washing: Centrifuge the eucommia gum microsphere dispersion obtained in the previous step at a centrifuge speed of 8000r / min for 20min, remove the emulsifier aqueous solution at the bottom of the centrifuge tube, add deionized water, shake thoroughly and then centrifuge, repeat this three times to obtain a high solid content eucommia gum microsphere dispersion without emulsifier residue.

[0114] Drying: The high solid content eucommia gum microsphere dispersion without emulsifier residue is placed in an oven at 45° C. for 18 hours to completely remove moisture to obtain eucommia gum microspheres.

[0115] Comparative Example 1

[0116] Preparation of oil phase: Add 50g of Eucommia gum and 950g of dichloromethane into a three-necked flask, heat to 30°C with a water bath, stir at 300r / min, and dissolve for 4h. Centrifuge the dissolved Eucommia gum solution at 16000r / min for 40min to remove impurities at the bottom of the centrifuge tube. Add 20.4g of polyoxyethylene ether to the Eucommia gum solution after impurity removal, stir with a glass rod until the polyoxyethylene ether is completely dissolved to form an oil phase.

[0117] Preparation of the aqueous phase: Pour 30g of sodium dodecylbenzene sulfonate into 1970g of deionized water, stir at 800r / min with a magnetic bar at 60°C until the sodium dodecylbenzene sulfonate is completely dissolved in the water to form an aqueous phase. Dissolve 20g of sodium hydroxide in 80g of water to prepare an alkaline solution, add the alkaline solution dropwise into the aqueous phase, and adjust the pH value of the solution to 13.

[0118] Emulsification: The speed of the homogenizer was adjusted to 2000r / min. Under the shearing action of the homogenizer, the oil phase was slowly added to the water phase. The ratio of oil phase to water phase was 1:2. After the oil phase was completely added, the speed of the homogenizer was adjusted to 8000r / min. Emulsification continued. However, the oil phase could not be evenly dispersed in the water phase and a colloidal dispersion could not be formed. Therefore, microspheres could not be prepared.

[0119] Comparative Example 2

[0120] Preparation of oil phase: Add 50g of Eucommia gum and 950g of dichloromethane into a three-necked flask, heat to 30°C with a water bath, stir at 300r / min, and dissolve for 4h. Centrifuge the dissolved Eucommia gum solution at 16000r / min for 40min to remove impurities at the bottom of the centrifuge tube. Add 20.4g of polyoxyethylene ether to the Eucommia gum solution after impurity removal, stir with a glass rod until the polyoxyethylene ether is completely dissolved to form an oil phase.

[0121] Preparation of water phase: Pour 2g of polyvinyl alcohol (1788 type) and 30g of sodium dodecylbenzene sulfonate into 1968g of deionized water, stir at 800r / min with a magnetic bar at 60°C until polyvinyl alcohol and sodium dodecylbenzene sulfonate are completely dissolved in water to form a water phase. Dissolve 20g of sodium hydroxide in 80g of water to prepare alkali solution, add the alkali solution dropwise into the water phase, and adjust the pH value of the solution to 13.

[0122] Emulsification: The speed of the homogenizer was adjusted to 2000r / min. Under the shearing action of the homogenizer, the oil phase was slowly added to the water phase. The ratio of oil phase to water phase was 1:2. After the oil phase was completely added, the speed of the homogenizer was adjusted to 8000r / min. Emulsification continued. However, the oil phase still could not be evenly dispersed in the water phase, and a colloidal dispersion could not be formed. Therefore, microspheres could not be prepared.

[0123] Figure 1 This is the apparent morphology of a certain amount of Eucommia gum microsphere sample obtained in Example 1 after drying. It can be seen that the Eucommia gum microspheres of the present invention are uniformly dispersed milky white substances.

[0124] The microspheres of Eucommia ulmoides prepared in Example 1 were characterized by SEM. Figure 2 , 3 .Depend on Figure 2 , 3 It can be seen that the microspheres are regular spherical in shape and have a smooth surface. Figure 4 The average particle size of the microspheres is about 11 μm, and the particle size distribution is narrow, which conforms to the normal distribution. The particle size of the eucommia gum microspheres prepared in Example 2, Example 3 and Example 4 was characterized by a nano laser particle size analyzer. The results show that Figure 5 The average particle size of the eucommia gum microspheres in each embodiment can be seen in Table 1, from which it can be concluded that the preparation method of the eucommia gum microspheres provided by the present invention, the average particle size of the microspheres can be controlled within the range of 500nm to 11μm by adjusting the formula and the preparation process according to actual needs.

[0125] Table 1

[0126]

[0127] It can be seen from Comparative Examples 1-2 and Examples 1-5 that the water-soluble emulsifier polyvinyl alcohol used in an amount of 0.5% to 5% of the mass of the aqueous phase is a necessary condition for forming the eucommia gum microspheres of the present invention with regular shape, smooth surface and narrow particle size distribution. The addition of several other emulsifiers can further adjust the average particle size of the microspheres. The eucommia gum microspheres prepared in the examples are regular solid spheres with a smooth surface, and can be directly used as gutta-percha fillings.

[0128] The preferred embodiments of the present invention have been specifically described above, but are not limited to the embodiments of the present invention. It is believed that experts in this field can make further modifications and improvements to the technical solutions of the present invention without violating the spirit of the invention, and all of them should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for preparing eucommia gum microspheres, characterized in that: The method comprises: (1) dissolving eucommia gum in a low boiling point organic solvent to prepare eucommia gum liquid; (2) centrifuging the eucommia gum liquid to remove impurities and form an oil phase; (3) dissolving a water-soluble emulsifier in deionized water to form an aqueous phase; the water-soluble emulsifier is polyvinyl alcohol; the amount of the polyvinyl alcohol is 0.5% to 5% of the mass of the aqueous phase; (4) Add the oil phase to the water phase under low-speed stirring, and then emulsify at high speed to obtain a rubber dispersion; (5) evaporating the gel dispersion to remove the organic solvent to obtain a microsphere dispersion; (6) Centrifuging and washing the microsphere dispersion to remove the residual emulsifier on the microspheres, and drying to obtain the eucommia gum microspheres.

2. The preparation method according to claim 1, characterized in that: In step (1), The eucommia gum is one or a combination of eucommia gum, gutta-percha, balata gum and euonymus gum; The low boiling point organic solvent is dichloromethane; The mass ratio of the low boiling point organic solvent to eucommia gum is (10-100): 1; The dissolution temperature is 25~30℃ and the dissolution time is 4~6h.

3. The preparation method according to claim 2, characterized in that: In step (1), The mass ratio of the low boiling point organic solvent to eucommia gum is (15-100):

1.

4. The preparation method according to claim 1, characterized in that: In step (2), after the Eucommia gum liquid is centrifuged to remove impurities, an oil-soluble emulsifier is added to form an oil phase; The oil-soluble emulsifier is one or a combination of polyoxyethylene ether and polyoxyethylene fatty alcohol ether; The amount of the oil-soluble emulsifier used is 1-5% of the mass of the oil phase.

5. The preparation method according to claim 4, characterized in that: In step (2), The amount of the oil-soluble emulsifier used is 1% to 2% of the mass of the oil phase.

6. The preparation method according to claim 1, characterized in that: In step (3), The amount of polyvinyl alcohol used is 0.7% to 2% of the mass of the water phase.

7. The preparation method according to claim 6, characterized in that: In step (3), The water-soluble emulsifier may also be added sodium dodecylbenzene sulfonate or sodium dodecyl sulfonate, and the pH value of the aqueous phase is adjusted to 10 to 13 with alkali solution; The mass ratio of the sodium dodecylbenzene sulfonate or sodium dodecyl sulfonate to polyvinyl alcohol is (0.5-2):1; The alkali solution is one of potassium hydroxide aqueous solution, sodium hydroxide aqueous solution and ammonia water, and the mass concentration of the alkali solution is 10% to 30%.

8. The preparation method according to claim 7, characterized in that: In step (3), Sodium dodecylbenzene sulfonate may also be added to the water-soluble emulsifier.

9. The preparation method according to claim 1, characterized in that: In step (4), The oil-water ratio of the oil phase to the water phase is 1:(1-4); The low speed is 2000-4000 r / min, and the high speed is 8000-10000 r / min; The emulsification time is 5~20min.

10. The preparation method according to claim 9, characterized in that: In step (4), The oil-water ratio of the oil phase to the water phase is 1:(1.5-2).

11. The preparation method according to claim 1, characterized in that: In step (5), The evaporation method is normal pressure evaporation, and the evaporation temperature is 30~40℃.

12. The preparation method according to claim 1, characterized in that: In step (6), The centrifugal speed is 5000~10000r / min, and the centrifugal time is 10~20min; The drying temperature is 30~55℃ and the drying time is 18~24h.

13. Eucommia gum microspheres prepared by the method according to any one of claims 1 to 12, characterized in that: The average particle size of the eucommia gum microspheres is 200nm-20μm.

14. The eucommia gum microspheres according to claim 13, characterized in that: The average particle size of the eucommia gum microspheres is 500nm-11μm.

15. Use of the eucommia gum microspheres according to claim 13 or 14 in preparing gutta-percha fillings.

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