A method for producing fine particles using method of rapid expansion into poor solvent from supercritical fluid
A technology of supercritical fluid and poor solvent, which is applied in the direction of liquid separation into beads and granulation, bulk chemical production, etc. It can solve the problems that the shape and dispersion cannot be controlled, the average particle size control of particles cannot be considered, and the adhesion of particles cannot be eliminated. , to achieve the effect of excellent dispersion
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[0027] The method for preparing polymer microparticles of the present invention includes the steps of dissolving or dispersing the polymer material in a high-pressure fluid containing a supercritical fluid and adding a solvent; and ejecting the obtained high-pressure fluid into a poor solvent to rapidly expand. In the present invention, the high-molecular material used as the raw material of fine particles is dissolved in a high-pressure fluid containing a supercritical fluid and an added solvent, and it is quickly sprayed into a poor solvent to cause supersaturated precipitation, thereby stably producing polymer particles.
[0028] In the present invention, "supercritical fluid" refers to a fluid at a temperature and pressure exceeding the critical temperature and critical pressure, and also includes a subcritical fluid. As such a supercritical fluid, its chemical type is not particularly limited. For example, an organic gas that is gaseous at normal temperature can be used....
Embodiment 1
[0064] Microparticles of polylactic acid were produced using the above apparatus.
[0065] First, 5 g of polylactic acid (molecular weight: 10,000) and 200 ml of ethanol as an additional solvent are added to the high-pressure chamber 15 in advance, and after filling the poor solvent chamber 21 with water as a poor solvent, these chambers 15 and 21 are respectively set at predetermined positions. Location.
[0066] Then, in the state of closing the valve V-2, supply carbon dioxide from the gas cylinder 1, the upper limit pressure of carbon dioxide is regulated by the pressure regulating valve V-1, and the temperature in the water constant temperature tank 18 is 313.15 ± 0.2K, so that the temperature of the protective tube is 350.15±0.5K. Next, with all the valves (V-4, V-5, and V-6) of the mixing section closed, the valve V-3 is opened to send carbon dioxide to the mixing section. Open the valve V-5 and let it stand for a period of time so that the specified pressure (25MPa) ...
Embodiment 2
[0071] Microparticles were prepared in the same manner as in Example 1 except that the reduced pressure conditions were changed. Specifically, open valve V-6, make indoor depressurization from 25MPa to 20MPa as shown in embodiment 1, from 20MPa decompression to 15MPa, and from 15MPa decompression to 10MPa, carry out rapid expansion injection in poor solvent, Recover particles. The particle size distribution of the poor solvent containing the fine particles was measured with a laser diffraction particle size distribution analyzer (SALD-2000, manufactured by Shimadzu Corporation). The result is as Figure 4 shown.
[0072] Depend on Figure 4 It can be seen that the average particle diameter can be controlled by changing the reduced pressure conditions.
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