Preparation method of eucommia gum microsphere dispersion liquid, eucommia gum microsphere dispersion liquid and application

Abstract

The present invention discloses a preparation method of eucommia gum microsphere dispersion liquid, an eucommia gum microsphere dispersion liquid and an application. The preparation method of the eucommia gum microsphere dispersion liquid of the present invention comprises: (1) dissolving eucommia gum in a low-boiling organic solvent to obtain an eucommia gum solution; (2) centrifuging the eucommia gum solution to remove impurities and then adding an oil-soluble emulsifier to form an oil phase; (3) dissolving a water-soluble emulsifier complex system in deionized water to form a water phase, and adjusting the pH value of the water phase with an alkali solution; (4) adding the oil phase to the water phase under low-speed stirring, and then emulsifying at a high speed to obtain a colloidal solution dispersion liquid; (5) evaporating and removing the organic solvent from the colloidal solution dispersion liquid to obtain a dilute microsphere dispersion liquid; (6) removing a part of the emulsifier aqueous solution from the dilute microsphere dispersion liquid successively at a low centrifugal speed and a high centrifugal speed, and obtaining the eucommia gum microsphere dispersion liquid after stirring and filtering. The preparation method of the present invention is energy-saving and time-saving, and the microsphere dispersion liquid can be uniformly dispersed in the latex as an additive.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation and application of polymer microsphere dispersions, and particularly to a preparation method of eucommia gum microsphere dispersions, eucommia gum microsphere dispersions and applications. Background Art

[0002] Eucommia gum is a bio-based polymer material with dual rubber and plastic properties synthesized in the body of Eucommia ulmoides, a unique economic tree species in China. 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 in Brazil. 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] On the one hand, existing medical gloves are natural latex gloves and nitrile gloves, and their cut resistance is poor. Eucommia gum has strong crystallization properties, and blending with other rubbers can endow the blended rubber with crystallization properties and improve the hardness of the blended rubber. Commercial eucommia gum is in block form, and only by dispersing eucommia gum into tiny latex particles or microspheres can it be added to other latexes.

[0004] Therefore, providing a eucommia gum material that can be uniformly dispersed in natural latex or nitrile latex and improve its comprehensive properties is a problem that needs to be solved currently. Summary of the Invention

[0005] To solve the problems existing in the prior art, the present invention provides a preparation method of eucommia gum microsphere dispersions, eucommia gum microsphere dispersions and applications. The eucommia gum microsphere dispersions of the present invention can be uniformly dispersed in natural latex and nitrile latex as an additive.

[0006] One of the purposes of the present invention is to provide a preparation method of eucommia gum microsphere dispersions.

[0007] The method includes:

[0008] (1) Dissolving eucommia gum in a low-boiling organic solvent to obtain an eucommia gum solution;

[0009] (2) Centrifuging the eucommia gum solution to remove impurities and then adding an oil-soluble emulsifier to form an oil phase;

[0010] (3) Dissolving a water-soluble emulsifier complex system in deionized water to form a water phase, and adjusting the pH value of the water phase with an alkali solution;

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

[0012] (5) Evaporating and removing the organic solvent from the colloidal solution dispersion to obtain a dilute microsphere dispersion;

[0013] (6) Remove a part of the aqueous emulsifier solution from the dilute microsphere dispersion successively at a low centrifugal speed and a high centrifugal speed, and obtain the eucommia gum microsphere dispersion after stirring and filtration.

[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 bungeanus maximowicz gum;

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

[0018] The mass ratio of the low-boiling organic solvent to the eucommia gum is (9-100):1, preferably (9-30):1, more preferably (9-20):1;

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

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

[0021] In step (2),

[0022] The oil-soluble emulsifier is polyoxyethylene ether;

[0023] The dosage of the polyoxyethylene ether is 1-2% of the mass of the oil phase, preferably 1.0-1.5%, more preferably 1.2%-1.5%.

[0024] In a preferred embodiment of the present invention,

[0025] In step (3),

[0026] The water-soluble emulsifier complex system is a combination of sodium dodecylbenzenesulfonate or sodium dodecylsulfonate and polyvinyl alcohol, preferably a combination of sodium dodecylbenzenesulfonate and polyvinyl alcohol;

[0027] In the water-soluble emulsifier complex system, the dosage of polyvinyl alcohol is 0.5-5% of the mass of the water phase, preferably 0.8-2%, more preferably 0.8-1.5%; the dosage of sodium dodecylbenzenesulfonate or sodium dodecylsulfonate is 1-2% of the mass of the water phase, preferably 1.2-1.5%.

[0028] The lye is one of potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, and ammonia water, the mass concentration of the lye is 10%-30%, and the pH value of the water phase is adjusted to 10-13.

[0029] In a preferred embodiment of the present invention,

[0030] In step (4),

[0031] The oil-water ratio of the oil phase to the water phase is 1:(1-4), preferably 1:(1.5-2);

[0032] The low rotation speed is 2000-4000 r / min, and the high rotation speed is 8000-10000 r / min;

[0033] The emulsification time is 5-20 min, preferably 10-15 min.

[0034] In a preferred embodiment of the present invention,

[0035] In step (5),

[0036] The evaporation method is atmospheric evaporation, and the evaporation temperature is 30-40 °C.

[0037] In a preferred embodiment of the present invention,

[0038] In step (6),

[0039] The low centrifugation speed is 4000-6000 r / min, and the centrifugation time is 8-12 min;

[0040] The high centrifugation speed is 12000-16000 r / min, and the centrifugation time is 10-15 min.

[0041] The second object of the present invention is to provide an eucommia gum microsphere dispersion obtained by the preparation method of the first object of the present invention.

[0042] The average particle size range of the microspheres in the dispersion is 500-1000 nm, and the solid content of the dispersion is 50-60%.

[0043] The third object of the present invention is the application of the eucommia gum microsphere dispersion of the second object of the present invention as an additive assistant for latex.

[0044] The latex is natural latex or nitrile latex;

[0045] When the eucommia gum microsphere dispersion is used as an additive assistant for natural latex, the eucommia gum content in the dried mixed latex is 10-20%;

[0046] When the eucommia gum microsphere dispersion is used as an additive assistant for nitrile latex, the eucommia gum content in the dried mixed latex is 10-40%.

[0047] The specific technical solution of the present invention is as follows:

[0048] The preparation of the eucommia gum microsphere dispersion preferably includes the following steps:

[0049] (1) Dissolve gutta-percha in a low-boiling organic solvent at a certain temperature to obtain a gutta-percha solution.

[0050] (2) Centrifuge the gutta-percha solution obtained in step (1) to remove impurities in the solution, and then dissolve an oil-soluble emulsifier in the gutta-percha solution after impurity removal to form an oil phase.

[0051] (3) Dissolve a water-soluble emulsifier complex system in deionized water to form an aqueous phase, and adjust the pH of the aqueous phase with an alkali solution.

[0052] (4) Under the stirring action of a homogenizer at a relatively low speed, add the oil phase slowly to the aqueous phase according to a certain oil-water ratio. After the oil phase is completely added, adjust the homogenizer to a relatively high speed and emulsify for a period of time to obtain a colloidal dispersion.

[0053] (5) Heat and stir the colloidal dispersion at a certain temperature to evaporate and remove the organic solvent. After the liquid level no longer drops, a dilute microsphere dispersion is obtained.

[0054] (6) Centrifuge the dilute microsphere dispersion at a low speed in sequence to make the solid content reach 20 - 30%, and then centrifuge at a high speed to make the solid content reach 50 - 60% to remove part of the emulsifier aqueous solution. After that, stir and filter to remove the aggregated gutta-percha microspheres during the centrifugation process to obtain the gutta-percha microsphere dispersion. The centrifugation process is divided into two steps because the centrifuge speed needs to reach more than 12,000 revolutions per minute to make the solid content reach 50 - 60%. However, if the volume of the dispersion is too large, it is not suitable to use a high-speed centrifuge. Therefore, part of the water is removed by low-speed centrifugation first and then high-speed centrifugation.

[0055] In step (1), the dissolution of gutta-percha is carried out by water bath heating, and a stirring paddle is used for stirring during the dissolution process. The rotation speed of the stirring paddle is 300 - 400 r / min.

[0056] In step (2), the rotation speed of the centrifuge required to remove insoluble impurities in the gutta-percha solution is 10,000 - 18,000 r / min, preferably 14,000 - 16,000 r / min, and the centrifugation time is 20 - 40 min.

[0057] In step (3), dissolve the emulsifier in water under the conditions of heating and stirring, and the heating temperature is 50 - 70°C.

[0058] In step (5), the rotation speed of the stirring paddle is 100 - 500 r / min, preferably 150 - 300 r / min.

[0059] The melting temperature of gutta-percha is relatively low, about 55 °C. When the temperature during solvent evaporation is higher than the melting temperature of gutta-percha, the solid gutta-percha microspheres in a dispersed state will be in a molten state. During the stirring process, the molten gutta-percha microspheres will collide and adhere to each other, resulting in the precipitation of aggregated gutta-percha. Therefore, an organic solvent with a low boiling point should be selected so that the organic solvent can be evaporated and removed at a temperature lower than the melting temperature of gutta-percha.

[0060] The principle and beneficial effects of the present invention are as follows:

[0061] Two necessary conditions are required for the formation of a stable (non-layered) microsphere dispersion of gutta-percha microspheres: one is that the particle size of the microspheres is small enough (less than 1000 nm), and the other is the addition of the oil-soluble emulsifier polyoxyethylene ether. Polyoxyethylene ether is insoluble in water and can form a film on the surface of the microspheres to separate the microspheres from each other, playing a role in preventing the aggregation of microspheres. Under the condition that other conditions in Example 1 remain unchanged, the influence of the dosage of polyoxyethylene ether on the particle size of the microspheres is as Figure 1 shown. Therefore, the key to whether the microspheres can form a stable microsphere dispersion lies in polyoxyethylene ether. In addition, polyvinyl alcohol is a necessary additive. Without polyvinyl alcohol or with an inappropriate amount of polyvinyl alcohol added, the oil phase cannot be emulsified.

[0062] Due to the presence of polar end groups, ester groups, in the gutta-percha of the present invention, the molecular chain has a certain polarity, which makes the gutta-percha of the present invention have good solubility in the polar solvent dichloromethane. The dissolution process can be completed in 4 - 6 hours at 25 - 30 °C, having the advantages of energy saving and time saving. Moreover, since dichloromethane has a low boiling point (39.75 °C) and is relatively easy to volatilize, the temperature required in the step of solvent evaporation is 30 - 40 °C, also having the advantage of energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a graph showing the influence of the dosage of polyoxyethylene ether on the average particle size of the microspheres under the condition that other conditions in Example 1 remain unchanged;

[0064] Figure 2 It is a particle size distribution diagram of the microspheres in the gutta-percha microsphere dispersion in Example 1;

[0065] Figure 3 It is a particle size distribution diagram of the microspheres in the gutta-percha microsphere dispersion in Example 2;

[0066] Figure 4 It is a particle size distribution diagram of the microspheres in the gutta-percha microsphere dispersion in Example 3;

[0067] Figure 5 It is a particle size distribution diagram of the microspheres in the gutta-percha microsphere dispersion in Comparative Example 3;

[0068] Figure 6SEM image of the Eucommia ulmoides gum microspheres in the Eucommia ulmoides gum microsphere dispersion prepared in Example 1, indicating that a layer of polyoxyethylene ether coats the outside of the microspheres;

[0069] Figure 7 Appearance photo of the Eucommia ulmoides gum microsphere dispersion with a solid content of 50% prepared in Example 1 after standing for one week. Detailed implementation manners

[0070] The present invention will be specifically described below in conjunction with specific drawings and examples. It is necessary to point out here that the following examples are only for further illustration of the present invention and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0071] All raw materials used in the examples are conventional commercially available raw materials.

[0072] The SEM image of the present invention was measured by a Hitachi S4800 scanning electron microscope;

[0073] The particle size of the present invention was measured by a ZetaPALS Zeta potential and particle size analyzer from Brookhaven Instruments Corporation, USA.

[0074] In the present invention: Tensile strength, 100% modulus at a specified elongation, 300% modulus at a specified elongation and modulus were detected according to the standard of GB / T 528-2009, tear strength was detected according to the standard of GB / T 529-2008, and the instrument used was a universal tensile machine (model: AL-7000S1, manufacturer: Taiwan High Speed Rail Testing Instruments Co., Ltd., China); Hardness was detected according to the standard of GB / T 531.1-2008, and the instrument used was a Shore A durometer (model: BS61, manufacturer: Beijing Ruida Yuchen Instruments Co., Ltd.).

[0075] Example 1

[0076] A preparation method of an Eucommia ulmoides gum microsphere dispersion

[0077] Preparation of the oil phase: Add 50 g of Eucommia ulmoides gum and 950 g of dichloromethane to a three-necked flask, heat it to 30 °C with a water bath, the rotation speed of the stirring paddle is 300 r / min, and the dissolution time is 4 h. Centrifuge the dissolved Eucommia ulmoides gum solution at a rotation speed of 16,000 r / min for 40 min to remove the impurities at the bottom of the centrifuge tube. Add 12 g of polyoxyethylene ether to the Eucommia ulmoides gum solution after impurity removal, and stir with a glass rod until the polyoxyethylene ether is completely dissolved to obtain the oil phase.

[0078] Preparation of the aqueous phase: Pour 16 g of polyvinyl alcohol (type 1788) and 30 g of sodium dodecylbenzenesulfonate into 1954 g of deionized water. At a temperature of 60 °C, use a magnetic stirrer to stir at a speed of 800 r / min until the polyvinyl alcohol is completely dissolved in the water to obtain the aqueous phase. Dissolve 20 g of sodium hydroxide in 80 g of water to prepare an alkaline solution, and add the alkaline solution dropwise to the aqueous phase to adjust the pH of the solution to 11.

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

[0080] Evaporation: Place the emulsified colloidal solution dispersion in a three-necked flask, heat it to 40 °C with a water bath, and use a stirring paddle to stir while evaporating dichloromethane. The speed of the stirring paddle is 300 r / min. Use a condensing device to recover the evaporated dichloromethane. When the liquid level in the flask no longer drops or there is no more distillate flowing out of the condenser tube, stop evaporation to obtain a dilute Eucommia ulmoides gum microsphere dispersion.

[0081] Concentration: Centrifuge the dilute Eucommia ulmoides gum microsphere dispersion obtained in the previous step at a centrifuge speed of 5000 r / min for 10 min. Remove a part of the emulsifier aqueous solution at the lower part of the centrifuge tube, stir to disperse the Eucommia ulmoides gum microspheres in the remaining emulsifier aqueous solution, filter after stirring for 5 min to obtain a Eucommia ulmoides gum microsphere dispersion with a solid content of 20%. Centrifuge the Eucommia ulmoides gum microsphere dispersion with a solid content of 20% at a centrifuge speed of 12000 r / min for 10 min, remove the emulsifier aqueous solution at the bottom of the centrifuge tube, stir to disperse the Eucommia ulmoides gum microspheres in the remaining emulsifier aqueous solution, filter after stirring for 5 min to obtain a Eucommia ulmoides gum microsphere dispersion with a solid content of 50% (i.e., the final product: Eucommia ulmoides gum microsphere dispersion). The average particle size of the Eucommia ulmoides gum microspheres in the Eucommia ulmoides gum microsphere dispersion is 531 nm, and the particle size distribution is as Figure 2 shown. The Eucommia ulmoides gum microsphere dispersion is relatively stable and no stratification phenomenon occurs after standing.

[0082] Example 2

[0083] A preparation method of Eucommia ulmoides gum microsphere dispersion

[0084] Preparation of the oil phase: Add 100 g of eucommia gum and 900 g of dichloromethane into a three-necked flask, heat it to 30 °C with a water bath, set the stirring paddle speed at 300 r / min, and dissolve for 4 h. Centrifuge the dissolved eucommia gum solution at a speed of 16,000 r / min for 40 min to remove impurities at the bottom of the centrifuge tube. Add 15 g of polyoxyethylene ether to the eucommia gum solution after impurity removal, and stir with a glass rod until the polyoxyethylene ether is completely dissolved to obtain the oil phase.

[0085] Preparation of the water phase: Pour 30 g of polyvinyl alcohol (type 1788) and 24 g of sodium dodecylbenzenesulfonate into 1946 g of deionized water, stir at 800 r / min with a magnetic stirrer at 60 °C until the polyvinyl alcohol is completely dissolved in water to obtain the water phase. Dissolve 20 g of sodium hydroxide in 80 g of water to prepare an alkali solution, and add the alkali solution dropwise to the water phase to adjust the pH of the solution to 13.

[0086] Emulsification: Adjust the speed of the homogenizer to 4000 r / min. Under the shearing action of the homogenizer, slowly add the oil phase to the water phase, with the ratio of the oil phase to the water phase being 1:2. After the oil phase is completely added, adjust the speed of the homogenizer to 8000 r / min and continue emulsifying for 10 min to obtain a colloidal solution dispersion.

[0087] Evaporation: Place the emulsified colloidal solution dispersion in a three-necked flask, heat it to 40 °C with a water bath, and evaporate dichloromethane while stirring with a stirring paddle at a speed of 300 r / min. Recover the evaporated dichloromethane with a condensing device. Stop evaporation when the liquid level in the flask no longer drops or no more distillate flows out of the condenser tube to obtain a dilute eucommia gum microsphere dispersion.

[0088] Concentration: Centrifuge the dilute eucommia gum microsphere dispersion obtained in the previous step at a centrifuge speed of 5000 r / min for 10 min, remove a part of the emulsifier aqueous solution at the lower part of the centrifuge tube, stir to disperse the eucommia gum microspheres in the remaining emulsifier aqueous solution, filter after stirring for 5 min to obtain a eucommia gum microsphere dispersion with a solid content of 20%. Centrifuge the eucommia gum microsphere dispersion with a solid content of about 20% at a centrifuge speed of 16,000 r / min for 10 min, remove the emulsifier aqueous solution at the bottom of the centrifuge tube, stir to disperse the eucommia gum microspheres in the remaining emulsifier aqueous solution, filter after stirring for 5 min to obtain a eucommia gum microsphere dispersion with a solid content of 60%. The average particle size of the eucommia gum microspheres in the dispersion is 875 nm, and the particle size distribution is as Figure 3 shown. The eucommia gum microsphere dispersion is relatively stable and no stratification phenomenon occurs after standing.

[0089] Example 3

[0090] A preparation method of eucommia gum microsphere dispersion

[0091] Preparation of the oil phase: Add 50 g of eucommia gum and 950 g of dichloromethane into a three-necked flask, heat it to 30 °C with a water bath, set the stirring paddle speed at 300 r / min, and dissolve for 4 h. Centrifuge the dissolved eucommia gum solution at a speed of 16,000 r / min for 40 min to remove the impurities at the bottom of the centrifuge tube. Add 12 g of polyoxyethylene ether to the eucommia gum solution after impurity removal, and stir with a glass rod until the polyoxyethylene ether is completely dissolved to obtain the oil phase.

[0092] Preparation of the water phase: Pour 12 g of polyvinyl alcohol (type 1788) and 22.5 g of sodium dodecylbenzenesulfonate into 1465.5 g of deionized water, stir at 800 r / min with a magnetic stirrer at 60 °C until the polyvinyl alcohol is completely dissolved in water to obtain the water phase. Dissolve 20 g of sodium hydroxide in 80 g of water to prepare an alkali solution, and add the alkali solution dropwise to the water phase to adjust the pH of the solution to 11.

[0093] Emulsification: Adjust the speed of the homogenizer to 4000 r / min. Under the shearing action of the homogenizer, slowly add the oil phase to the water phase, with the ratio of the oil phase to the water phase being 1:1.5. After the oil phase is completely added, adjust the speed of the homogenizer to 8000 r / min and continue emulsifying for 10 min to obtain a colloidal solution dispersion.

[0094] Evaporation: Place the emulsified colloidal solution dispersion in a three-necked flask, heat it to 40 °C with a water bath, and evaporate dichloromethane while stirring with a stirring paddle at a speed of 300 r / min. Use a condensing device to recover the evaporated dichloromethane. Stop evaporation when the liquid level in the flask no longer drops or there is no distillate flowing out of the condenser tube to obtain a dilute eucommia gum microsphere dispersion.

[0095] Concentration: Centrifuge the dilute eucommia gum microsphere dispersion obtained in the previous step at a centrifuge speed of 5000 r / min for 10 min, remove a part of the emulsifier aqueous solution at the lower part of the centrifuge tube, stir to disperse the eucommia gum microspheres in the remaining emulsifier aqueous solution, filter after stirring for 5 min to obtain a eucommia gum microsphere dispersion with a solid content of 20%. Centrifuge the eucommia gum microsphere dispersion with a solid content of 20% at a centrifuge speed of 12,000 r / min for 10 min, remove the emulsifier aqueous solution at the bottom of the centrifuge tube, stir to disperse the eucommia gum microspheres in the remaining emulsifier aqueous solution, filter after stirring for 5 min to obtain a eucommia gum microsphere dispersion with a solid content of 50% (i.e., the final product: eucommia gum microsphere dispersion). The average particle size of the eucommia gum microspheres in the eucommia gum microsphere dispersion is 691 nm, and the particle size distribution is as Figure 4 shown. The eucommia gum microsphere dispersion is relatively stable and no stratification phenomenon occurs after standing.

[0096] Comparative Example 1

[0097] Preparation of the oil phase: Add 50 g of eucommia gum and 950 g of dichloromethane into a three-necked flask, heat it to 30 °C with a water bath, set the stirring paddle speed at 300 r / min, and dissolve for 4 h. Centrifuge the dissolved eucommia gum solution at a speed of 16,000 r / min for 40 min to remove impurities at the bottom of the centrifuge tube. Add 12 g of polyoxyethylene ether to the eucommia gum solution after impurity removal, and stir with a glass rod until the polyoxyethylene ether is completely dissolved to form the oil phase.

[0098] Preparation of the water phase: Pour 30 g of sodium dodecylbenzenesulfonate into 1970 g of deionized water, and stir at a speed of 800 r / min with a magnetic stirrer at 60 °C until the sodium dodecylbenzenesulfonate is completely dissolved in water to form the water phase. Dissolve 20 g of sodium hydroxide in 80 g of water to prepare an alkali solution, and add the alkali solution dropwise to the water phase to adjust the pH value of the solution to 11.

[0099] Emulsification: Adjust the speed of the homogenizer to 4000 r / min. Under the shearing action of the homogenizer, slowly add the oil phase to the water phase. The ratio of the oil phase to the water phase is 1:2, and the oil phase cannot be emulsified by the water phase.

[0100] Comparative Example 2

[0101] Preparation of the oil phase: Add 50 g of eucommia gum and 950 g of dichloromethane into a three-necked flask, heat it to 30 °C with a water bath, set the stirring paddle speed at 300 r / min, and dissolve for 4 h. Centrifuge the dissolved eucommia gum solution at a speed of 16,000 r / min for 40 min to remove impurities at the bottom of the centrifuge tube. Add 12 g of polyoxyethylene ether to the eucommia gum solution after impurity removal, and stir with a glass rod until the polyoxyethylene ether is completely dissolved to obtain the oil phase.

[0102] Preparation of the water phase: Pour 2 g of polyvinyl alcohol (type 1788) and 30 g of sodium dodecylbenzenesulfonate into 1968 g of deionized water, and stir at a speed of 800 r / min with a magnetic stirrer at 60 °C until the polyvinyl alcohol is completely dissolved in water to obtain the water phase. Dissolve 20 g of sodium hydroxide in 80 g of water to prepare an alkali solution, and add the alkali solution dropwise to the water phase to adjust the pH to 11.

[0103] Emulsification: Adjust the speed of the homogenizer to 4000 r / min. Under the shearing action of the homogenizer, slowly add the oil phase to the water phase. The ratio of the oil phase to the water phase is 1:2, and the oil phase cannot be emulsified by the water phase.

[0104] Comparative Example 3

[0105] A preparation method of eucommia gum microsphere dispersion

[0106] Preparation of the oil phase: Add 50 g of gutta-percha and 950 g of dichloromethane into a three-necked flask, heat it to 30 °C with a water bath, set the stirring paddle speed at 300 r / min, and dissolve for 4 h. Centrifuge the dissolved gutta-percha solution at 16,000 r / min for 40 min to remove impurities at the bottom of the centrifuge tube, and obtain the oil phase.

[0107] Preparation of the aqueous phase: Pour 16 g of polyvinyl alcohol (type 1788) and 30 g of sodium dodecylbenzenesulfonate into 1954 g of deionized water, stir at 800 r / min with a magnetic stirrer at 60 °C until the polyvinyl alcohol is completely dissolved in water to obtain the aqueous phase. Dissolve 20 g of sodium hydroxide in 80 g of water to prepare an alkali solution, and add the alkali solution dropwise to the aqueous phase to adjust the pH of the solution to 11.

[0108] Emulsification: Adjust the speed of the homogenizer to 4000 r / min. Under the shearing action of the homogenizer, slowly add the oil phase to the aqueous phase. The ratio of the oil phase to the aqueous phase is 1:2. After the oil phase is completely added, adjust the speed of the homogenizer to 8000 r / min and continue emulsifying for 10 min to obtain a colloidal solution dispersion.

[0109] Evaporation: Place the emulsified colloidal solution dispersion in a three-necked flask, heat it to 40 °C with a water bath, and evaporate dichloromethane while stirring with a stirring paddle at a speed of 300 r / min. Recover the evaporated dichloromethane with a condensing device. Stop evaporation when the liquid level in the flask no longer drops or no more distillate flows out of the condenser tube, and obtain a dilute gutta-percha microsphere dispersion.

[0110] Concentration: Centrifuge the dilute gutta-percha microsphere dispersion obtained in the previous step at 5000 r / min for 10 min, remove a part of the emulsifier aqueous solution at the lower part of the centrifuge tube, stir to disperse the gutta-percha microspheres in the remaining emulsifier aqueous solution, filter after stirring for 5 min to obtain a gutta-percha microsphere dispersion with a solid content of 20%. Centrifuge the gutta-percha microsphere dispersion with a solid content of 20% at 12,000 r / min for 10 min, remove the emulsifier aqueous solution at the bottom of the centrifuge tube, stir to disperse the gutta-percha microspheres in the remaining emulsifier aqueous solution, filter after stirring for 5 min to obtain a gutta-percha microsphere dispersion with a solid content of 50% (i.e., the final product: gutta-percha microsphere dispersion). The average particle size of the gutta-percha microspheres in the gutta-percha microsphere dispersion is 3179 nm, and the particle size distribution is as Figure 5 shown. The dispersion prepared under these conditions is unstable and shows a layering phenomenon after standing.

[0111] Comparative Example 4

[0112] A preparation method of a gutta-percha microsphere dispersion

[0113] Preparation of the oil phase: Add 50 g of Eucommia ulmoides gum and 950 g of dichloromethane into a three-necked flask, heat it to 30 °C with a water bath, set the stirring paddle speed at 300 r / min, and dissolve for 4 h. Centrifuge the dissolved Eucommia ulmoides gum solution at 16,000 r / min for 40 min to remove impurities at the bottom of the centrifuge tube. Add 15 g of nonylphenol polyoxyethylene ether to the Eucommia ulmoides gum solution after impurity removal, and stir with a glass rod until the polyoxyethylene ether is completely dissolved to obtain the oil phase.

[0114] Preparation of the aqueous phase: Pour 30 g of polyvinyl alcohol (type 1788) and 24 g of sodium dodecylbenzenesulfonate into 1946 g of deionized water, and stir with a magnetic stirrer at 800 r / min at 60 °C until the polyvinyl alcohol is completely dissolved in water to obtain the aqueous phase. Dissolve 20 g of sodium hydroxide in 80 g of water to prepare an alkali solution, and add the alkali solution dropwise to the aqueous phase to adjust the pH of the solution to 13.

[0115] Emulsification: Adjust the speed of the homogenizer to 4000 r / min. Under the shearing action of the homogenizer, slowly add the oil phase to the aqueous phase. The ratio of the oil phase to the aqueous phase is 1:2, and the oil phase cannot be emulsified by the aqueous phase.

[0116] Figure 6 is the microscopic picture of the microspheres in the Eucommia ulmoides gum microsphere dispersion of Example 1, indicating that a layer of polyoxyethylene ether coats the outside of the microspheres; Figure 7 is the macroscopic picture of the Eucommia ulmoides gum microsphere dispersion of Example 1 standing for one week. It can be seen that the Eucommia ulmoides gum microsphere dispersion prepared under this condition is relatively stable, without stratification, and can be stably stored for more than one week.

[0117] It can be seen from Examples 1-3 and Comparative Examples 1-4 that the key to whether the microspheres can form a stable microsphere dispersion lies in polyoxyethylene ether. The average particle size of the microspheres in the Eucommia ulmoides gum microsphere dispersion is in the range of less than 1000 nm, and a stable (non-stratifying) microsphere dispersion can be formed only when the dosage of polyoxyethylene ether is within the scope of the present invention; in addition, polyvinyl alcohol is a necessary additive. Without polyvinyl alcohol or with an inappropriate amount of polyvinyl alcohol added, the oil phase cannot be emulsified.

[0118] Application of the Eucommia ulmoides gum microsphere dispersion

[0119] 1. Blending with natural latex

[0120] Preparation of the microsphere dispersion: Use the Eucommia ulmoides gum microsphere dispersion prepared in Example 1;

[0121] Blend the Eucommia ulmoides gum microsphere dispersion with natural latex to obtain a mixed latex;

[0122] The vulcanization system is shown in Table 1:

[0123] Table 1

[0124] Formulation Compound latex Sulfur Accelerator Zinc oxide 20% KOH Dosage (parts) 100 1 1 0.5 0.1

[0125] The solid content of natural latex is 60%. After adding natural latex, Eucommia ulmoides gum microsphere dispersion and various compounding agents in proportion, stir for 30 min, then filter and lay the film. After the film is dried, put it into an oven at 100 °C for vulcanization for 1 h.

[0126] The mechanical properties of the rubber films with different Eucommia ulmoides gum contents (Eucommia ulmoides gum content = mass of Eucommia ulmoides gum microsphere dispersion * solid content / (mass of Eucommia ulmoides gum microsphere dispersion * solid content + natural latex * solid content) * 100%, ignoring the influence of emulsifier) are shown in Table 2:

[0127] Table 2

[0128]

[0129] It can be seen from Table 2 that adding an appropriate amount of Eucommia ulmoides gum dispersion can significantly improve the tear resistance of the vulcanized rubber film. When the content of Eucommia ulmoides gum is 20%, the tear strength of the vulcanized rubber film can reach 42.63 kN / m, which is 19.04% higher than that of the vulcanized rubber film with 0% Eucommia ulmoides gum content. In addition, with the increase of the Eucommia ulmoides gum content, the modulus, 100% modulus at elongation, 300% modulus at elongation and Shore A hardness of the vulcanized rubber film increase significantly, and the tensile strength decreases but remains at a relatively high level.

[0130] 2. Blending with nitrile latex

[0131] The preparation of Eucommia ulmoides gum microsphere dispersion is the same as that in Example 1. The solid content of Eucommia ulmoides gum microsphere dispersion is 50%, and the average particle size of the microspheres is 531 nm.

[0132] The Eucommia ulmoides gum microsphere dispersion is blended with nitrile latex to obtain a blended latex;

[0133] The vulcanization system is shown in Table 3:

[0134] Table 3

[0135]

[0136] The solid content of nitrile latex is 40%. After adding nitrile latex, Eucommia ulmoides gum microsphere dispersion and various compounding agents in proportion, stir for 30 min, then filter and lay the film. After the film is dried, put it into an oven at 110 °C for vulcanization for 2 h.

[0137] The mechanical properties of the rubber films with different Eucommia ulmoides gum contents (Eucommia ulmoides gum content = mass of Eucommia ulmoides gum microsphere dispersion * solid content / (mass of Eucommia ulmoides gum microsphere dispersion * solid content + natural latex * solid content) * 100%, ignoring the influence of emulsifier) are shown in Table 4:

[0138] Table 4

[0139]

[0140] As can be seen from Table 4, with the increase of the content of Eucommia ulmoides gum, the 100% modulus at elongation, 300% modulus at elongation and Shore A hardness of the vulcanized rubber film increase significantly, indicating that the dimensional stability of the rubber film is significantly improved. In addition, with the increase of the content of Eucommia ulmoides gum, the tear strength of the vulcanized film of nitrile latex also shows an increasing trend; and the tensile strength of the vulcanized film of nitrile latex, with the increase of the content of Eucommia ulmoides gum, not only does not show a continuous decreasing trend, but is significantly improved. Compared with the rubber film prepared from pure nitrile latex, when the content of Eucommia ulmoides gum is 30%, the tensile strength is increased by 155.21% and the tear strength is increased by 76.02%, achieving good technical effects.

[0141] The preferred embodiments of the present invention have been specifically described above, but are not limited to the described embodiments of the present invention. It is believed that experts in the field can make further modifications and improvements to the technical solutions of the present invention without departing from the spirit of the invention, and all should fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a eucommia gum microsphere dispersion, characterized in that: The method includes: (1) Dissolving eucommia gum in a low-boiling organic solvent to obtain a eucommia gum solution; (2) Centrifuging the eucommia gum solution to remove impurities and then adding an oil-soluble emulsifier to form an oil phase; the oil-soluble emulsifier is polyoxyethylene ether; (3) Dissolving a water-soluble emulsifier complex system in deionized water to form a water phase, and adjusting the pH value of the water phase with an alkali solution; the water-soluble emulsifier complex system is a combination of sodium dodecylbenzenesulfonate or sodium dodecylsulfonate and polyvinyl alcohol; (4) Under low-speed stirring, adding the oil phase to the water phase, and then emulsifying at high speed to obtain a gum solution dispersion; (5) Evaporating and removing the organic solvent from the gum solution dispersion to obtain a dilute microsphere dispersion; (6) Removing part of the emulsifier aqueous solution from the dilute microsphere dispersion at a low centrifugal speed and then at a high centrifugal speed, and obtaining the eucommia gum microsphere dispersion after stirring and filtering; wherein, the low centrifugal speed is 4000-6000 r / min, and the high centrifugal speed is 12000-16000 r / min.

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 bungeanus maximowiczii gum; The low-boiling organic solvent is dichloromethane; The mass ratio of the low-boiling organic solvent to eucommia gum is (9-100):1; The dissolution temperature is 25-30 °C, and the dissolution time is 4-6 h.

3. The preparation method according to claim 2, characterized in that: In step (1), The mass ratio of the low-boiling organic solvent to eucommia gum is (9-30):

1.

4. The preparation method according to claim 1, characterized in that: In step (2), The dosage of the polyoxyethylene ether is 1-2% of the mass of the oil phase.

5. The preparation method according to claim 4, characterized in that: In step (2), The dosage of the polyoxyethylene ether is 1.0%-1.5% of the mass of the oil phase.

6. The preparation method according to claim 5, characterized in that: In step (2), The dosage of the polyoxyethylene ether is 1.2%-1.5% of the mass of the oil phase.

7. The preparation method according to claim 1, characterized in that: In step (3), The water-soluble emulsifier complex system is a combination of sodium dodecylbenzenesulfonate and polyvinyl alcohol; The dosage of polyvinyl alcohol in the water-soluble emulsifier complex system is 0.5-5% of the mass of the water phase, and the dosage of sodium dodecylbenzenesulfonate or sodium dodecylsulfonate is 1-2% of the mass of the water phase.

8. The preparation method according to claim 7, characterized in that: In step (3), The dosage of polyvinyl alcohol in the water-soluble emulsifier complex system is 0.8-2% of the mass of the water phase, and the dosage of sodium dodecylbenzenesulfonate or sodium dodecylsulfonate is 1.2-1.5% of the mass of the water phase.

9. The preparation method according to claim 1, characterized in that: In step (3), The alkali solution is one of potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, and ammonia water, the mass concentration of the alkali solution is 10%-30%, and the pH value of the water phase is adjusted to 10-13.

10. 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 rotation speed is 2000 - 4000 r / min, and the high rotation speed is 8000 - 10000 r / min; the emulsification time is 5 - 20 min.

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

12. The preparation method according to claim 1, characterized in that: In step (5), the evaporation method is atmospheric evaporation, and the evaporation temperature is 30 - 40 °C.

13. The preparation method according to claim 1, characterized in that: In step (6), the centrifugation time for low rotation speed centrifugation is 8 - 12 min; the centrifugation time for high rotation speed centrifugation is 10 - 15 min.

14. A Eucommia ulmoides gum microsphere dispersion liquid prepared by the method according to any one of claims 1 - 13, characterized in that: the average particle size range of the microspheres in the dispersion liquid is 500 - 1000 nm, and the solid content of the dispersion liquid is 50 - 60%.

15. An application of a Eucommia ulmoides gum microsphere dispersion liquid according to claim 14 as an additive assistant for latex, characterized in that: the latex is natural latex or nitrile latex; when the Eucommia ulmoides gum microsphere dispersion liquid is used as an additive assistant for natural latex, the Eucommia ulmoides gum content in the dried mixed latex is 10 - 20%; when the Eucommia ulmoides gum microsphere dispersion liquid is used as an additive assistant for nitrile latex, the Eucommia ulmoides gum content in the dried mixed latex is 10 - 40%.

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