Preparation method and application of walnut-shaped polypropylene micron particles
By heating and stirring polypropylene and organic solvent in a specific atmosphere, warm phase separation and solvent removal are carried out to prepare walnut-shaped polypropylene microparticles, solving the problem of preparation of polypropylene microparticles, and achieving efficient preparation and superhydrophobic surface effects.
Patent Information
- Application Number
- CN202211094509.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-08
- Publication Date
- 2025-04-18
- Estimated Expiration
- 2042-09-08
AI Technical Summary
The prior art is difficult to effectively prepare polypropylene microparticles, especially in morphological regulation, but there is a lack of technical support.
Walnut-shaped polypropylene microparticles were prepared during drying by heating and stirring the polypropylene and organic solvent in a specific atmosphere until completely dissolved, followed by warm phase separation and solvent removal.
It realizes the efficient preparation of polypropylene microparticles, with superhydrophobic surface, and is suitable for the fields of adsorption materials and hydrophobic materials.
Smart Images
Figure CN115368590B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of polymer ultrafine powders, and specifically relates to a preparation method and application of walnut-shaped polypropylene micron particles by controlling the polypropylene granulation process by a physical method. Background Art
[0002] Common preparation methods for polymer micron particles mainly include emulsion polymerization, microemulsion polymerization, miniemulsion polymerization, soap-free emulsion polymerization, suspension polymerization, dispersion polymerization, precipitation polymerization and seed swelling polymerization. Polypropylene (PP for short) is one of the most common general-purpose plastics. Due to its excellent properties, low density, high temperature resistance, good tensile strength and stiffness, polypropylene is widely used in machinery, aviation, electronics and furniture.
[0003] However, polypropylene cannot be prepared into micron particles by dispersion polymerization or emulsion polymerization like other polymers such as polystyrene, which brings great difficulties to the preparation of polypropylene micron particles. Some researchers use solution recrystallization method to dissolve polypropylene in xylene to obtain a uniform solution, and then freeze-dry it in liquid nitrogen to obtain polypropylene micron particles. At present, there are very limited research reports on the preparation and production of polypropylene micron particles, and there is a lack of technology for regulating the morphology of polypropylene micron particles. Summary of the invention
[0004] In view of the deficiencies in the prior art, the present invention provides a method for preparing polypropylene micron particles and applications thereof.
[0005] The present invention comprises the following steps:
[0006] (1) Weigh a certain amount of polypropylene and organic solvent and place them in a reactor. Heat and stir until the polypropylene is completely dissolved.
[0007] (2) placing the transparent solution obtained in step (1) in a specific atmosphere, allowing the polypropylene solution to undergo thermotropic phase separation at a certain temperature for a certain period of time, and then removing the solvent at a certain temperature.
[0008] (3) Drying the product obtained in step (2) at a certain temperature to obtain walnut-shaped polypropylene micron particles.
[0009] Preferably, the polypropylene raw material in step (1) is isotactic or syndiotactic polypropylene, and the weight average molecular weight is 12000-340000; further, the polypropylene raw material in step (1) is isotactic polypropylene.
[0010] Preferably, the organic solvent in step (1) is a chlorinated hydrocarbon or an aromatic hydrocarbon, and further, the organic solvent is decahydronaphthalene (cis / trans mixed isomers).
[0011] Preferably, in step (1), the mass ratio of polypropylene to organic solvent is 0.5-10%.
[0012] Preferably, the specific atmosphere in step (2) is air.
[0013] Preferably, the temperature-induced phase separation in step (2) lasts for 2 minutes to 2 hours, depending on the feed amount; the set temperature for the temperature-induced phase separation is 80°C.
[0014] Preferably, the temperature for removing the organic solvent in step (2) is set at 50-60°C; the duration is 30 minutes to 48 hours, which is related to the amount of feed.
[0015] Preferably, the drying time in step (3) is 1-48 hours, which is related to the amount of feed; and the drying temperature is 70°C.
[0016] The walnut-shaped polypropylene micron particles prepared in the above steps can be used in adsorption materials and hydrophobic materials.
[0017] The present invention has the following beneficial effects:
[0018] 1. The preparation materials only require polypropylene and organic solvents. The raw materials are simple and easy to obtain, and the purity of the product can be guaranteed.
[0019] 2. The surface structure of the obtained micronized particles can be regulated by the solvent removal temperature, and the mass ratio of polypropylene to solvent can be used to regulate the average diameter of the particles.
[0020] 3. The operation is simple, the feasibility is high, and the equipment requirements are low. The obtained walnut-shaped polypropylene micron particles have a super-hydrophobic surface. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 is a SEM image of polypropylene micron particles obtained in Example 1;
[0022] Figure 2 is a SEM image of walnut-shaped polypropylene microparticles obtained in Example 2;
[0023] Figure 3 is a SEM image of walnut-shaped polypropylene microparticles obtained in Example 3;
[0024] Figure 4 is a SEM image of the polypropylene film obtained in Example 4;
[0025] Figure 5 is a SEM image of walnut-shaped polypropylene microparticles obtained in Example 5;
[0026] Figure 6 is a SEM image of walnut-shaped polypropylene microparticles obtained in Example 6;
[0027] Figure 7 is the BET surface area of polypropylene microparticles at different solvent removal temperatures with a mass ratio of polypropylene to solvent of 10%;
[0028] Figure 8 This is a graph of the water contact angle of walnut-shaped polypropylene microparticles. DETAILED DESCRIPTION
[0029] In order to further understand the present invention, the embodiments of the present invention will be further described in detail below in combination with examples and comparative examples, but the embodiments of the present invention are not limited thereto.
[0030] Example 1
[0031] (1) Add a certain amount of polypropylene to decalin with a mass ratio of polypropylene to solvent of 10% and heat and stir at 140 °C until it is completely dissolved.
[0032] (2) The transparent solution obtained in step (1) was placed in an air atmosphere, and the phase separation temperature was set to 80° C. and the phase separation time was 10 minutes. Then, the solvent removal stage was entered, and the solvent removal temperature was 40° C. and the duration was 12 hours.
[0033] (3) Drying the product obtained in step (2) at 70° C. for 12 hours to obtain non-walnut-shaped polypropylene micron particles, such as Figure 1 shown.
[0034] Example 2
[0035] (1) Add a certain amount of polypropylene to decalin with a mass ratio of polypropylene to solvent of 10% and heat and stir at 140 °C until it is completely dissolved.
[0036] (2) The transparent solution obtained in step (1) was placed in an air atmosphere, and the phase separation temperature was set to 80° C. and the phase separation time was 10 minutes. Then, the solvent removal stage was entered, and the solvent removal temperature was 50° C. and the duration was 12 hours.
[0037] (3) The product obtained in step (2) is dried at 70° C. for 12 hours to obtain walnut-shaped polypropylene micron particles, such as Figure 2 shown.
[0038] Example 3
[0039] (1) Add a certain amount of polypropylene to decalin with a mass ratio of polypropylene to solvent of 10% and heat and stir at 140 °C until it is completely dissolved.
[0040] (2) The transparent solution obtained in step (1) was placed in an air atmosphere, and the phase separation temperature was set to 80° C. and the phase separation time was 10 minutes. Then, the solvent removal stage was entered, and the solvent removal temperature was 60° C. and the duration was 12 hours.
[0041] (3) The product obtained in step (2) is dried at 70° C. for 12 hours to obtain walnut-shaped polypropylene micron particles, such as Figure 3 shown.
[0042] Example 4
[0043] (1) Add a certain amount of polypropylene to decalin with a mass ratio of polypropylene to solvent of 10% and heat and stir at 140 °C until it is completely dissolved.
[0044] (2) The transparent solution obtained in step (1) was placed in an air atmosphere, and the phase separation temperature was set to 80° C. and the phase separation time was 10 minutes. Then, the solvent removal stage was entered, and the solvent removal temperature was 80° C. and the duration was 12 hours.
[0045] (3) Drying the product obtained in step (2) at 70° C. for 12 hours to obtain a polypropylene film, such as Figure 4 As shown, the high solvent removal temperature resulted in film formation and no walnut-shaped polypropylene microparticles were formed.
[0046] Example 5
[0047] (1) Add a certain amount of polypropylene to decalin with a mass ratio of polypropylene to solvent of 0.5% and heat and stir at 140 °C until it is completely dissolved.
[0048] (2) The transparent solution obtained in step (1) was placed in an air atmosphere, and the phase separation temperature was set to 80° C. and the phase separation time was 10 minutes. Then, the solvent removal stage was entered, and the solvent removal temperature was 60° C. and the duration was 12 hours.
[0049] (3) The product obtained in step (2) is dried at 70° C. for 12 hours to obtain walnut-shaped polypropylene micron particles, such as Figure 5 shown.
[0050] Example 6
[0051] (1) Add a certain amount of polypropylene to decalin with a mass ratio of 5% polypropylene to solvent, and heat and stir at 140 °C until it is completely dissolved.
[0052] (2) The transparent solution obtained in step (1) was placed in an air atmosphere, and the phase separation temperature was set to 80° C. and the phase separation time was 10 minutes. Then, the solvent removal stage was entered, and the solvent removal temperature was 60° C. and the duration was 12 hours.
[0053] (3) The product obtained in step (2) is dried at 70° C. for 12 hours to obtain walnut-shaped polypropylene micron particles, such as Figure 6 shown.
[0054] Figure 7 The data show the change trend of the BET surface area of polypropylene microparticles with different solvent removal temperatures when the mass ratio of polypropylene to solvent is fixed at 10%. It can be seen that when the solvent removal temperature is 40°C, the BET surface area is only 2.6573 m 2 / g, and when the solvent removal temperature was 50 °C, the BET surface area increased significantly to 5.7639 m 2 / g, while when the solvent removal temperature is 60 °C, the growth rate of BET surface area slows down to 6.2111m 2 / g. Combined SEM images of the three ( Figure 1 , Figure 2 , Figure 3 ) It can be inferred that the morphology of polypropylene particles has a decisive influence on their BET surface area. When the solvent removal temperature is 40 °C, the particles are non-walnut-shaped and have few surface pores. When the solvent removal temperature is 50-60 °C, the particles are walnut-shaped and the pores are significantly increased, resulting in a significant increase in the BET surface area. The morphology can be regulated by the solvent removal temperature, that is, the surface structure morphology can be regulated by the solvent removal temperature, thereby changing its BET surface area.
[0055] Figure 8 What is shown is the water contact angle of walnut-shaped polypropylene microparticles. It can be seen that the water contact angle of the layer formed by walnut-shaped polypropylene microparticles is 147°. This is because the surface of the walnut-shaped polypropylene particles is porous and easy to form an air layer, making it super hydrophobic, which can be used in the field of hydrophobic materials in the future.
[0056] In summary, the present invention uses polypropylene and corresponding organic solvents as raw materials, obtains an organic solvent suspension containing polypropylene particles by temperature-induced phase separation, and then extracts polypropylene micron particles by removing the organic solvent. Among them, the mass ratio of polypropylene to solvent can be used to control the average diameter of the particles (5-20μm), and the surface structure morphology can be controlled by the temperature during solvent removal to obtain walnut-shaped polypropylene micron particles. The present invention has the advantages of simple raw materials, simple process, and low equipment requirements, and is expected to be used in the fields of adsorption materials, hydrophobic materials, etc. in the future.
Claims
1. A method for preparing walnut-shaped polypropylene micron particles, characterized in that: The following steps are involved: (1) Weigh a certain amount of polypropylene and organic solvent and place them in a reaction kettle, heat and stir until the polypropylene is completely dissolved; (2) placing the transparent solution obtained in step (1) in a specific atmosphere, allowing the polypropylene solution to undergo thermotropic phase separation at a certain temperature for a certain period of time, and then removing the organic solvent at a certain temperature; (3) drying the product obtained in step (2) at a certain temperature to obtain walnut-shaped polypropylene micron particles; In the step (1), the polypropylene raw material is isotactic or syndiotactic polypropylene, and the weight average molecular weight is 12000-340000; The organic solvent in step (1) is decahydronaphthalene; In step (1), the mass ratio of polypropylene to organic solvent is 0.5%-10%; The temperature of the temperature-induced phase separation in step (2) is set at 80° C. and the duration is 2 minutes to 2 hours; In the step (2), the temperature for removing the organic solvent is set at 50-60° C. and the duration is 30 minutes to 48 hours.
2. The method for preparing walnut-shaped polypropylene micron particles according to claim 1, characterized in that: The specific atmosphere in step (2) is air.
3. The method for preparing walnut-shaped polypropylene micron particles according to claim 1, characterized in that: The drying temperature in step (3) is 70° C. and the drying time is 1-48 hours.